An Improper Authentication vulnerability [CWE-287] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.2, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11, FortiWeb 7.2.0 through 7.2.12, FortiWeb 7.0.0 through 7.0.12 may allow a remote unauthenticated attacker to login into the Fortiweb GUI/CLI with a random username and password

Summary

Terrapin is a prefix truncation attack targeting the SSH protocol. More precisely, Terrapin breaks the integrity of SSH's secure channel. By carefully adjusting the sequence numbers during the handshake, an attacker can remove an arbitrary amount of messages sent by the client or server at the beginning of the secure channel without the client or server noticing it.

Mitigations

To mitigate this protocol vulnerability, OpenSSH suggested a so-called "strict kex" which alters the SSH handshake to ensure a Man-in-the-Middle attacker cannot introduce unauthenticated messages as well as convey sequence number manipulation across handshakes.

Warning: To take effect, both the client and server must support this countermeasure.

As a stop-gap measure, peers may also (temporarily) disable the affected algorithms and use unaffected alternatives like AES-GCM instead until patches are available.

Details

The SSH specifications of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (-etm@openssh.com MACs) are vulnerable against an arbitrary prefix truncation attack (a.k.a. Terrapin attack). This allows for an extension negotiation downgrade by stripping the SSHMSGEXTINFO sent after the first message after SSHMSGNEWKEYS, downgrading security, and disabling attack countermeasures in some versions of OpenSSH. When targeting Encrypt-then-MAC, this attack requires the use of a CBC cipher to be practically exploitable due to the internal workings of the cipher mode. Additionally, this novel attack technique can be used to exploit previously unexploitable implementation flaws in a Man-in-the-Middle scenario.

The attack works by an attacker injecting an arbitrary number of SSHMSGIGNORE messages during the initial key exchange and consequently removing the same number of messages just after the initial key exchange has concluded. This is possible due to missing authentication of the excess SSHMSGIGNORE messages and the fact that the implicit sequence numbers used within the SSH protocol are only checked after the initial key exchange.

In the case of ChaCha20-Poly1305, the attack is guaranteed to work on every connection as this cipher does not maintain an internal state other than the message's sequence number. In the case of Encrypt-Then-MAC, practical exploitation requires the use of a CBC cipher; while theoretical integrity is broken for all ciphers when using this mode, message processing will fail at the application layer for CTR and stream ciphers.

For more details see https://terrapin-attack.com.

Impact

This attack targets the specification of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (-etm@openssh.com), which are widely adopted by well-known SSH implementations and can be considered de-facto standard. These algorithms can be practically exploited; however, in the case of Encrypt-Then-MAC, we additionally require the use of a CBC cipher. As a consequence, this attack works against all well-behaving SSH implementations supporting either of those algorithms and can be used to downgrade (but not fully strip) connection security in case SSH extension negotiation (RFC8308) is supported. The attack may also enable attackers to exploit certain implementation flaws in a man-in-the-middle (MitM) scenario.

A security regression (CVE-2006-5051) was discovered in OpenSSH's server (sshd). There is a race condition which can lead sshd to handle some signals in an unsafe manner. An unauthenticated, remote attacker may be able to trigger it by failing to authenticate within a set time period.

An improper verification of cryptographic signature vulnerability in Fortinet FortiWeb 8.0.0, FortiWeb 7.6.0 through 7.6.4, FortiWeb 7.4.0 through 7.4.9 may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.

A improper verification of cryptographic signature vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2.0 through 7.2.11, FortiOS 7.0.0 through 7.0.17, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4.0 through 7.4.10, FortiProxy 7.2.0 through 7.2.14, FortiProxy 7.0.0 through 7.0.21, FortiSwitchManager 7.2.0 through 7.2.6, FortiSwitchManager 7.0.0 through 7.0.5 allows an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.

An out-of-bounds write vulnerability [CWE-787] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may allow a remote privileged attacker to execute arbitrary code or command via crafted HTTP requests.

A improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiManager 7.6.0 through 7.6.1, FortiManager 7.4.1 through 7.4.3, FortiManager Cloud 7.4.1 through 7.4.3, FortiOS 7.6.0, FortiOS 7.4.0 through 7.4.4, FortiOS 7.2.0 through 7.2.9, FortiOS 7.0.0 through 7.0.15, FortiOS 6.4.0 through 6.4.15, FortiProxy 7.4.0 through 7.4.5, FortiProxy 7.2.0 through 7.2.11, FortiProxy 7.0.0 through 7.0.18, FortiProxy 2.0 all versions, FortiProxy 1.2 all versions, FortiProxy 1.1 all versions, FortiProxy 1.0 all versions may allow a remote authenticated attacker with access to the security fabric interface and port to write arbitrary files or a remote unauthenticated attacker to delete an arbitrary folder

A improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiRecorder 7.2.0 through 7.2.1, FortiRecorder 7.0.0 through 7.0.4, FortiVoice 7.0.0 through 7.0.4, FortiVoice 6.4.0 through 6.4.9, FortiVoice 6.0 all versions, FortiWeb 7.6.0, FortiWeb 7.4.0 through 7.4.4, FortiWeb 7.2 all versions, FortiWeb 7.0 all versions, FortiWeb 6.4 all versions allows attacker to escalate privilege via specially crafted packets.

An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] in FortiOS, FortiManager, FortiAnalyzer, FortiProxy, FortiSwitchManager, FortiWeb may allow an attacker with a FortiCloud account and a registered device to log into other devices registered to other accounts, if FortiCloud SSO authentication is enabled on those devices.Please note that the FortiCloud SSO login feature is not enabled in default factory settings. However, when an administrator registers the device to FortiCare from the device's GUI, unless the administrator disables the toggle switch "Allow administrative login using FortiCloud SSO" in the registration page, FortiCloud SSO login is enabled upon registration. This vulnerability was found being exploited in the wild by two malicious FortiCloud accounts, which were locked out on 2026-01-22. In order to protect its customers from further exploit, Fortinet disabled FortiCloud SSO on FortiCloud side on 2026-01-26. It was re-enabled on 2026-01-27 and no longer supports login from devices running vulnerable versions. Consequently, customers must upgrade to the latest versions listed below for the FortiCloud SSO authentication to function.FortiManager Cloud, FortiAnalyzer Cloud, FortiGate Cloud are NOT impacted.Setups with Custom IdP for SSO instead of FortiCloud are not impacted (including setups using FortiAuthenticator as the Custom IdP)

A relative path traversal vulnerability [CWE-23] in FortiWeb may allow an unauthenticated attacker to execute administrative commands on the system via crafted HTTP or HTTPS requests. Fortinet has observed this to be exploited in the wild FortiAppSec Cloud is NOT impacted by this vulnerability.

An Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability [CWE-78] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.1, FortiWeb 7.6.0 through 7.6.5, FortiWeb 7.4.0 through 7.4.10, FortiWeb 7.2.0 through 7.2.11, FortiWeb 7.0.0 through 7.0.11 may allow an authenticated attacker to execute unauthorized code on the underlying system via crafted HTTP requests or CLI commands.

An improper neutralization of special elements used in an SQL command ('SQL Injection') vulnerability [CWE-89] in FortiWeb may allow an unauthenticated attacker to execute unauthorized SQL code or commands via crafted HTTP or HTTPs requests.

A fundamental design flaw within the RADIUS protocol has been proven to be exploitable, compromising the integrity in the RADIUS Access-Request process. The attack allows a malicious user to modify packets in a way that would be indistinguishable to a RADIUS client or server. To be successful, the attacker must have the ability to inject themselves between the client and server.

A integer overflow or wraparound vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4 all versions, FortiWeb 7.2 all versions, FortiWeb 7.0 all versions may allow attacker to denial of service via <insert attack vector here>

A improper neutralization of special elements used in an os command ('os command injection') vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.1, FortiWeb 7.6.0 through 7.6.5, FortiWeb 7.4.0 through 7.4.11, FortiWeb 7.2.0 through 7.2.12, FortiWeb 7.0.0 through 7.0.12 may allow an authenticated attacked to execute arbitrary commands via a specialy crafted HTTP request.

An Improper Control of Interaction Frequency vulnerability [CWE-799] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.2, FortiWeb 7.6.0 through 7.6.5, FortiWeb 7.4.0 through 7.4.10, FortiWeb 7.2.0 through 7.2.11, FortiWeb 7.0.0 through 7.0.11 may allow a remote unauthenticated attacker to bypass the authentication rate-limit via crafted requests. The success of the attack depends on the attacker's resources and the password target complexity.

A use of externally-controlled format string vulnerability [CWE-134] in FortiOS version 7.4.0 through 7.4.4, version 7.2.0 through 7.2.9, version 7.0.0 through 7.0.15 and before 6.4.15, FortiProxy version 7.4.0 through 7.4.6, version 7.2.0 through 7.2.12 and before 7.0.19, FortiPAM version 1.4.0 through 1.4.2 and before 1.3.1, FortiSRA version 1.4.0 through 1.4.2 and before 1.3.1 and FortiWeb version 7.4.0 through 7.4.5, version 7.2.0 through 7.2.10 and before 7.0.10 allows a privileged attacker to execute unauthorized code or commands via specially crafted HTTP or HTTPS commands.

An Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability [CWE-22] in FortiWeb endpoint may allow an authenticated admin to access and modify the filesystem via crafted requests.

A improper restriction of communication channel to intended endpoints vulnerability [CWE-923] in Fortinet FortiOS version 7.4.0 through 7.4.4, 7.2.0 through 7.2.8, 7.0.0 through 7.0.15, 6.4.0 through 6.4.15 and before 6.2.16, Fortinet FortiProxy version 7.4.0 through 7.4.2, 7.2.0 through 7.2.9 and before 7.0.15, Fortinet FortiManager version 7.4.0 through 7.4.2, 7.2.0 through 7.2.4, 7.0.0 through 7.0.11, 6.4.0 through 6.4.14 and before 6.2.13, Fortinet FortiAnalyzer version 7.4.0 through 7.4.2, 7.2.0 through 7.2.4, 7.0.0 through 7.0.11, 6.4.0 through 6.4.14 and before 6.2.13, Fortinet FortiVoice version 7.0.0 through 7.0.2 before 6.4.8 and Fortinet FortiWeb before 7.4.2 may allow an unauthenticated attacker in a man-in-the-middle position to impersonate the management device (FortiCloud server or/and in certain conditions, FortiManager), via intercepting the FGFM authentication request between the management device and the managed device

An Improper Privilege Management vulnerability [CWE-269] affecting FortiOS, FortiProxy & FortiWeb may allow an authenticated attacker with at least read-only admin permissions to gain super-admin privileges via crafted requests to Node.js websocket module.

An improper neutralization of special elements used in an OS command ('OS Command Injection') vulnerability [CWE-78] in Fortinet FortiWeb version 7.6.0 through 7.6.3, 7.4.0 through 7.4.7, 7.2.0 through 7.2.10 and before 7.0.10 allows an authenticated privileged attacker to execute unauthorized code or commands via crafted CLI commands

A reliance on cookies without validation and integrity checking vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.1, FortiWeb 7.6.0 through 7.6.5, FortiWeb 7.4.0 through 7.4.10, FortiWeb 7.2.0 through 7.2.11, FortiWeb 7.0.0 through 7.0.11 may allow an unauthenticated attacker to execute arbitrary operations on the system via crafted HTTP or HTTPS request via forged cookies, requiring prior knowledge of the FortiWeb serial number.

A insertion of sensitive information into sent data vulnerability in Fortinet FortiMail 7.4.0 through 7.4.2, FortiMail 7.2.0 through 7.2.6, FortiMail 7.0 all versions, FortiManager 7.6.0 through 7.6.1, FortiManager 7.4.1 through 7.4.3, FortiManager Cloud 7.4.1 through 7.4.3, FortiNDR 7.6.0 through 7.6.1, FortiNDR 7.4.0 through 7.4.8, FortiNDR 7.2 all versions, FortiNDR 7.1 all versions, FortiNDR 7.0 all versions, FortiNDR 1.5 all versions, FortiOS 7.6.0, FortiOS 7.4.0 through 7.4.4, FortiOS 7.2.0 through 7.2.8, FortiOS 7.0.0 through 7.0.15, FortiOS 6.4.0 through 6.4.15, FortiOS 6.2 all versions, FortiOS 6.0 all versions, FortiPAM 1.3 all versions, FortiPAM 1.2 all versions, FortiPAM 1.1 all versions, FortiPAM 1.0 all versions, FortiProxy 7.4.0 through 7.4.4, FortiProxy 7.2.0 through 7.2.10, FortiProxy 7.0 all versions, FortiProxy 2.0 all versions, FortiProxy 1.2 all versions, FortiProxy 1.1 all versions, FortiProxy 1.0 all versions, FortiRecorder 7.2.0 through 7.2.1, FortiRecorder 7.0.0 through 7.0.4, FortiTester 7.4.0 through 7.4.2, FortiTester 7.3 all versions, FortiTester 7.2 all versions, FortiTester 7.1 all versions, FortiTester 7.0 all versions, FortiTester 4.2 all versions, FortiVoice 7.0.0 through 7.0.4, FortiVoice 6.4.0 through 6.4.9, FortiVoice 6.0.7 through 6.0.12, FortiWeb 7.6.0, FortiWeb 7.4.0 through 7.4.4, FortiWeb 7.2 all versions, FortiWeb 7.0 all versions, FortiWeb 6.4 all versions allows attacker to disclose sensitive information via specially crafted packets.

An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] in FortiOS, FortiManager, FortiAnalyzer, FortiProxy, FortiSwitchManager, FortiWeb may allow an attacker with a FortiCloud account and a registered device to log into other devices registered to other accounts, if FortiCloud SSO authentication is enabled on those devices.Please note that the FortiCloud SSO login feature is not enabled in default factory settings. However, when an administrator registers the device to FortiCare from the device's GUI, unless the administrator disables the toggle switch "Allow administrative login using FortiCloud SSO" in the registration page, FortiCloud SSO login is enabled upon registration. This vulnerability was found being exploited in the wild by two malicious FortiCloud accounts, which were locked out on 2026-01-22. In order to protect its customers from further exploit, Fortinet disabled FortiCloud SSO on FortiCloud side on 2026-01-26. It was re-enabled on 2026-01-27 and no longer supports login from devices running vulnerable versions. Consequently, customers must upgrade to the latest versions listed below for the FortiCloud SSO authentication to function.FortiManager Cloud, FortiAnalyzer Cloud, FortiGate Cloud are NOT impacted.Setups with Custom IdP for SSO instead of FortiCloud are not impacted (including setups using FortiAuthenticator as the Custom IdP)

A improper handling of parameters in Fortinet FortiWeb versions 7.6.3 and below, versions 7.4.7 and below, versions 7.2.10 and below, and 7.0.10 and below may allow an unauthenticated remote attacker with non-public information pertaining to the device and targeted user to gain admin privileges on the device via a specially crafted request.

A use of password hash instead of password for authentication vulnerability [CWE-836] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.1, FortiWeb 7.6.0 through 7.6.5, FortiWeb 7.4.0 through 7.4.10, FortiWeb 7.2.0 through 7.2.11, FortiWeb 7.0.0 through 7.0.11 may allow an unauthenticated attacker to use the hash in place of the password to authenticate via crafted HTTP/HTTPS requests

A Relative Path Traversal vulnerability [CWE-23] in FortiWeb 7.6.0 through 7.6.4, 7.4.0 through 7.4.8, 7.2.0 through 7.2.11, 7.0.2 through 7.0.11 may allow an authenticated attacker to perform an arbitrary file read on the underlying system via crafted requests.

An Improper Verification of Cryptographic Signature vulnerability[CWE-347] in FortiOS, FortiWeb, FortiProxy and FortiSwitchManager mayallow an unauthenticated attacker to bypass the FortiCloud SSO loginauthentication via a crafted SAML message, if that feature is enabled on the device. Please note that the FortiCloud SSO login feature is not enabled in default factory settings. However, when an administrator registers the device to FortiCare from the device's GUI, unless the administrator disables the toggle switch "Allow administrative login using FortiCloud SSO" in the registration page, FortiCloud SSO login is enabled upon registration. To prevent being affected by this vulnerability on vulnerableversions, please turn off the FortiCloud login feature (if enabled) temporarily untilupgrading to a non-affected version.To turn off FortiCloud login, go to System -> Settings -> Switch"Allow administrative login using FortiCloud SSO" to Off. Or type thefollowing command in the CLI: config system global set admin-forticloud-sso-login disableend

A improper restriction of communication channel to intended endpoints vulnerability [CWE-923] in Fortinet FortiOS version 7.4.0 through 7.4.3, 7.2.0 through 7.2.7, 7.0.0 through 7.0.14, 6.4.0 through 6.4.15 and 6.2.0 through 6.2.16, Fortinet FortiProxy version 7.4.0 through 7.4.2, 7.2.0 through 7.2.9, 7.0.0 through 7.0.15 and 2.0.0 through 2.0.14, Fortinet FortiManager version 7.4.0 through 7.4.2, 7.2.0 through 7.2.4, 7.0.0 through 7.0.11, 6.4.0 through 6.4.14 and 6.2.0 through 6.2.13, Fortinet FortiAnalyzer version 7.4.0 through 7.4.2, 7.2.0 through 7.2.4, 7.0.0 through 7.0.11, 6.4.0 through 6.4.14 and 6.2.0 through 6.2.13, Fortinet FortiVoice version 7.0.0 through 7.0.2, 6.4.0 through 6.4.8 and 6.0.0 through 6.0.12 and Fortinet FortiWeb version 7.4.0 through 7.4.2, 7.2.0 through 7.2.10, 7.0.0 through 7.0.10 allows an unauthenticated attacker in a man-in-the-middle position to impersonate the management device (FortiCloud server or/and in certain conditions, FortiManager), via intercepting the FGFM authentication request between the management device and the managed device

An Incorrect User Management vulnerability [CWE-286] in FortiWeb version 7.6.2 and below, version 7.4.6 and below, version 7.2.10 and below, version 7.0.11 and below widgets dashboard may allow an authenticated attacker with at least read-only admin permission to perform operations on the dashboard of other administrators via crafted requests.