A client-side enforcement of server-side security [CWE-602] vulnerability in FortiManager and FortiAnalyzer may allow a remote attacker with low privileges to access a privileged web console via client side code execution.

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 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 use of potentially Dangerous Function vulnerability [CWE-676] in FortiAnalyzer and FortiManager API may allow an authenticated attacker to cause a system hang via multiple specially crafted HTTP requests causing crashes. This happens if internal locks are aligned, which is out of control of the attacker.

A use of potentially Dangerous Function vulnerability [CWE-676] in FortiAnalyzer and FortiManager API may allow an authenticated attacker to cause a system hang via multiple specially crafted HTTP requests causing crashes. This happens if internal locks are aligned, which is out of control of the attacker.

An improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in FortiAnalyzer, FortiAnalyzer Cloud, FortiManager and FortiManager Cloud may allow a privileged attacker to delete files from the underlying filesystem via crafted CLI requests.

An improper neutralization of special elements used in an SQL command ('SQL injection') [CWE-89] in FortiAnalyzer, FortiAnalyzer Cloud, FortiManager and FortiManager Cloud may allow an authenticated privileged attacker to execute unauthorized code or commands via crafted requests.

An improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in FortiAnalyzer, FortiAnalyzer Cloud, FortiManager and FortiManager Cloud may allow a privileged attacker to delete files from the underlying filesystem via crafted CLI requests.

A improper certificate validation vulnerability in Fortinet FortiAnalyzer 7.6.0 through 7.6.4, FortiAnalyzer 7.4.0 through 7.4.8, FortiAnalyzer 7.2 all versions, FortiAnalyzer 7.0 all versions, FortiAnalyzer 6.4 all versions, FortiManager 7.6.0 through 7.6.4, FortiManager 7.4.0 through 7.4.8, FortiManager 7.2 all versions, FortiManager 7.0 all versions, FortiManager 6.4 all versions may allow a remote unauthenticated attacker to view confidential information via a man in the middle [MiTM] attack.

An Inclusion of Undocumented Features [CWE-1242] in FortiManager and FortiAnalyzer CLI may allow a remote authenticated read-only admin with CLI access to escalate their privilege via use of a hidden command.

An authentication bypass using an alternate path or channel vulnerability [CWE-288] in FortiManager and FortiAnalyzer multifactor authentication may allow an attacker with knowledge of the admins password to bypass multifactor authentication checks via submitting multiple crafted requests.

An improper certificate validation [CWE-295] vulnerability in the FortiManager GUI may allow a remote unauthenticated attacker to view confidential information via a man in the middle [MiTM] attack.

A use of externally-controlled format string vulnerability [CWE-134] in FortiAnalyzer, FortiAnalyzer Cloud, FortiManager and FortiManager Cloud fazsvcd daemon may allow a remote privileged attacker with admin profile to execute arbitrary code or commands via specially crafted requests.

Multiple improper neutralization of special elements used in an os command ('os command injection') in Fortinet FortiManager, FortiAnalyzer versions 7.4.0 through 7.4.2 7.2.0 through 7.2.5 and 7.0.0 through 7.0.12 and 6.4.0 through 6.4.14 and 6.2.0 through 6.2.12 and 6.0.0 through 6.0.12 and 5.6.0 through 5.6.11 and 5.4.0 through 5.4.7 and 5.2.0 through 5.2.10 and 5.0.0 through 5.0.12 and 4.3.4 through 4.3.8 allows attacker to execute unauthorized code or commands via crafted CLI requests.

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.

A use of externally-controlled format string vulnerability [CWE-134] in FortiManager, FortiAnalyzer, FortiAnalyzer-BigData & FortiPortal may allow a privileged attacker to execute unauthorized code or commands via specially crafted command arguments.

A externally controlled reference to a resource in another sphere vulnerability in Fortinet allows attacker to poison web caches via crafted HTTP requests, where the Host header points to an arbitrary webserver

A key management error vulnerability [CWE-320] in FortiManager, FortiAnalyzer and FortiPortal may allow an authenticated admin to retrieve a certificate's private key via the device's admin shell.

A key management error vulnerability [CWE-320] in FortiManager, FortiAnalyzer and FortiPortal may allow an authenticated admin to retrieve a certificate's private key via the device's admin shell.

A buffer overflow [CWE-121] in the TFTP client library of FortiOS before 6.4.7 and FortiOS 7.0.0 through 7.0.2, may allow an authenticated local attacker to achieve arbitrary code execution via specially crafted command line arguments.

Two improper neutralization of special elements used in an SQL Command ('SQL Injection') vulnerability [CWE-89] in FortiAnalyzer, FortiManager & FortiAnalyzer-BigData may allow a privileged attacker to execute unauthorized code or commands via specifically crafted CLI requests.

An improper limitation of a pathname to a restricted directory ('Path Traversal') vulnerability [CWE-22] in FortiManager and FortiAnalyzer CLI may allow any authenticated admin user with diagnose privileges to delete any file on the system.

An insertion of sensitive information into log file vulnerabilities [CWE-532] in FortiAnalyzer and FortiManager eventlog may allow any low privileged user with access to event log section to retrieve certificate private key and encrypted password logged as system log.

An Improper Output Neutralization for Logs vulnerability [CWE-117] in FortiAnalyzer version 7.6.1 and below, version 7.4.5 and below, version 7.2.8 and below, version 7.0.13 and below and FortiManager version 7.6.1 and below, version 7.4.5 and below, version 7.2.8 and below, version 7.0.12 and below may allow an unauthenticated remote attacker to pollute the logs via crafted login requests.

A missing authorization [CWE-862] vulnerability in FortiManager may allow an authenticated attacker to overwrite global threat feeds via crafted update requests.

An Improper Output Neutralization for Logs vulnerability [CWE-117] in FortiManager and FortiAnalyzer may allow an unauthenticated remote attacker to pollute the logs via crafted login requests.

A relative path traversal vulnerability [CWE-23] in FortiManager administrative interface may allow a privileged attacker to delete files from the underlying filesystem via crafted HTTP or HTTPs requests.

Multiple improper neutralization of special elements used in an OS command ('OS Command Injection') vulnerabilities [CWE-78] in FortiManager CLI may allow a privileged attacker to execute unauthorized code or commands via crafted CLI requests.

Two improper neutralization of special elements used in an SQL Command ('SQL Injection') vulnerability [CWE-89] in FortiAnalyzer, FortiManager & FortiAnalyzer-BigData may allow a privileged attacker to execute unauthorized code or commands via specifically crafted CLI requests.

CVE-2025-26466A flaw was found in the OpenSSH package. For each ping packet the SSH server receives, a pong packet is allocated in a memory buffer and stored in a queue of packages. It is only freed when the server/client key exchange has finished. A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side. Consequently, the server may become unavailable, resulting in a denial of service attack.