A improper restriction of rendered ui layers or frames vulnerability in Fortinet FortiPAM Chrome Extension 8.0 all versions, FortiPAM Chrome Extension 7.4 all versions may allow attacker to information disclosure via remote unauthenticated attack

A incomplete list of disallowed inputs vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.2, FortiWeb 7.6.0 through 7.6.5, FortiWeb 7.4 all versions, FortiWeb 7.2 all versions, FortiWeb 7.0 all versions may allow attacker to improper access control via <insert attack vector here>

An Insufficient Session Expiration vulnerability [CWE-613] in FortiOS SSL VPN 7.6.0 through 7.6.2, 7.4.0 through 7.4.6, 7.2.0 through 7.2.10, 7.0.0 through 7.0.16, 6.4 all versions may allow a remote attacker (e.g. a former admin whose account was removed and whose session was terminated) in possession of the SAML record of a user session to access or re-open that session via re-use of SAML record.

A inclusion of sensitive information in source code vulnerability in Fortinet FortiMonitorOnSight 7.2.4 through 7.2.7, FortiMonitorOnSight 7.2.0 through 7.2.2 may allow attacker to improper access control via <insert attack vector here>

A heap-based buffer overflow vulnerability [CWE-122] in FortiOS and FortiSwitchManager cwacd daemon may allow a remote unauthenticated attacker to execute arbitrary code or commands via specifically crafted requests.The presence of security controls such as ASLR and PIE considerably raises the complexity and preparation effort required for exploitation.

A improper validation of certificate with host mismatch vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6, FortiProxy 7.6.2 through 7.6.6 may allow attacker to information disclosure via <insert attack vector here>

A url redirection to untrusted site ('open redirect') vulnerability in Fortinet FortiSIEM 7.5.0 through 7.5.1, FortiSIEM 7.4.1 through 7.4.2 may allow attacker to execute unauthorized code or commands via <insert attack vector here>

A improper access control vulnerability in Fortinet FortiSOAR PaaS 7.6.0 through 7.6.6, FortiSOAR PaaS 7.5.0 through 7.5.3, FortiSOAR PaaS 7.4 all versions, FortiSOAR PaaS 7.3 all versions, FortiSOAR on-premise 7.6.0 through 7.6.6, FortiSOAR on-premise 7.5.0 through 7.5.3, FortiSOAR on-premise 7.4 all versions, FortiSOAR on-premise 7.3 all versions may allow attacker to escalation of privilege via <insert attack vector here>

TL;DR. The FortiPAM Chrome extension (1M+ users), used for Privileged Access Management, allowed any site to set the browser's proxy for the session, alongside allowing any site to create a new tab and send screen recordings of it to an attacker's server. That makes for trivial phishing attacks which only require the user to view something sensitive in the attacker-opened tab. CVSS 9.1 | CVE-2026-84388.

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Fortinet FortiSandbox. Authentication is required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 7.2. The following CVEs are assigned: CVE-2026-84387.

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Fortinet FortiSandbox. Authentication is required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 7.2. The following CVEs are assigned: CVE-2026-84387.

A buffer copy without checking size of input ('classic buffer overflow') vulnerability in Fortinet FortiClientWindows 7.4.0 through 7.4.3, FortiClientWindows 7.2.0 through 7.2.11 may allow an unauthenticated attacker in a position to alter or craft DNS responses to the targeted host to execute arbitrary code via malicious packets.

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

A server-side request forgery (ssrf) vulnerability in Fortinet FortiSIEM 7.5.0, FortiSIEM 7.4.0 through 7.4.2, FortiSIEM 7.3.0 through 7.3.5, FortiSIEM 7.2 all versions, FortiSIEM 7.1 all versions, FortiSIEM 7.0 all versions, FortiSIEM 6.7 all versions, FortiSIEM 6.6 all versions, FortiSIEM 6.5 all versions may allow attacker to execute unauthorized code or commands via <insert attack vector here>

A authentication bypass using an alternate path or channel vulnerability in Fortinet FortiManager 7.6.1, FortiManager 7.4.3 through 7.4.5, FortiManager 7.2.5 through 7.2.9, FortiManager Cloud 7.6.1, FortiManager Cloud 7.4.3 through 7.4.5, FortiManager Cloud 7.2.5 through 7.2.9 may allow attacker to improper access control via <insert attack vector here>

A Stack-based Buffer Overflow vulnerability [CWE-121] vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6 may allow an unauthenticated attacker who can bypass stack protection and ASLR to execute arbitrary code or commands in the context of the WAD daemon via crafted sockets, only if the explicit proxy is configured with Kerberos authentication and SOCKS enabled.

A allocation of resources without limits or throttling vulnerability in Fortinet FortiOS 7.6.0 through 7.6.6, FortiOS 7.4 all versions, FortiOS 7.2 all versions may allow attacker to denial of service via <insert attack vector here>

An improper access control vulnerability in Fortinet FortiManager 7.6.0 through 7.6.4, FortiManager 7.4.0 through 7.4.10, FortiManager 7.2 all versions, FortiManager Cloud 7.6.2 through 7.6.4, FortiManager Cloud 7.4.1 through 7.4.10, FortiManager Cloud 7.2 all versions may allow an administrator to bypass the approval process for workflow sessions via crafted HTTP or HTTPs requests.

A improper access control vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.5, FortiSandbox 4.4.0 through 4.4.8, FortiSandbox Cloud 5.0.4 through 5.0.5, FortiSandbox PaaS 5.0.4 through 5.0.5 may allow attacker to access sensitive information via crafted HTTP requests.

A use of uninitialized variable vulnerability in Fortinet FortiAnalyzer 7.6.3 through 7.6.6 may allow attacker to denial of service via <insert attack vector here>

A NULL Pointer Dereference vulnerability [CWE-476] vulnerability in Fortinet FortiOS 7.4 all versions, FortiOS 7.2 all versions, FortiPAM 1.9.0, FortiPAM 1.8 all versions, FortiPAM 1.7 all versions, FortiPAM 1.6 all versions, FortiPAM 1.5 all versions, FortiPAM 1.4 all versions, FortiPAM 1.3 all versions, FortiPAM 1.2 all versions, FortiPAM 1.1 all versions, FortiPAM 1.0 all versions, FortiProxy 7.6.0 through 7.6.6, FortiProxy 7.4 all versions, FortiProxy 7.2 all versions may allow an authenticated attacker to crash the httpsd daemon via crafted HTTP requests.

A improper neutralization of special elements used in a command ('command injection') vulnerability in Fortinet FortiSandbox 5.2.0, FortiSandbox 5.0.0 through 5.0.6, FortiSandbox 4.4.0 through 4.4.9 may allow attacker to execute unauthorized code or commands via <insert attack vector here>

A unverified ownership vulnerability in Fortinet FortiClientWindows 7.4.0 through 7.4.7, FortiClientWindows 7.2 all versions may allow attacker to improper access control via <insert attack vector here>

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.

A improper neutralization of special elements used in an os command ('os command injection') vulnerability in Fortinet FortiADC 7.6.0 through 7.6.1, FortiADC 7.4.0 through 7.4.6, FortiADC 7.2.0 through 7.2.7, FortiADC 7.1.0 through 7.1.4, FortiADC 7.0 all versions, FortiADC 6.2 all versions, FortiADC 6.1 all versions, FortiADC 6.0 all versions, FortiADC 5.4 all versions, FortiADC 5.3 all versions, FortiADC 5.2 all versions, FortiADC 5.1 all versions, FortiADC 5.0 all versions, FortiADC 4.8 all versions, FortiADC 4.7 all versions, FortiADC 4.6 all versions, FortiADC 4.5 all versions, FortiADC 4.4 all versions, FortiADC 4.3 all versions, FortiADC 4.2 all versions, FortiADC 4.1 all versions, FortiADC 4.0 all versions, FortiADC 3.2 all versions, FortiADC 3.1 all versions, FortiADC 3.0 all versions may allow attacker to execute unauthorized code or commands via <insert attack vector here>

A session fixation vulnerability [CWE-384] in FortiOS may allow an unauthenticated attacker to hijack user session via a phishing SAML authentication link.

An improper neutralization of special elements used in an OS command ('OS Command Injection') vulnerability [CWE-78] vulnerability in Fortinet FortiSIEM 7.3.0 through 7.3.1, FortiSIEM 7.2.0 through 7.2.5, FortiSIEM 7.1.0 through 7.1.7, FortiSIEM 7.0.0 through 7.0.3, FortiSIEM 6.7.0 through 6.7.9, FortiSIEM 6.6 all versions, FortiSIEM 6.5 all versions, FortiSIEM 6.4 all versions, FortiSIEM 6.3 all versions, FortiSIEM 6.2 all versions, FortiSIEM 6.1 all versions, FortiSIEM 5.4 all versions, FortiSIEM 5.3 all versions, FortiSIEM 5.2 all versions, FortiSIEM 5.1 all versions, FortiSIEM 5.0 all versions, FortiSIEM 4.10 all versions, FortiSIEM 4.9 all versions, FortiSIEM 4.7 all versions allows an unauthenticated attacker to execute unauthorized code or commands via crafted CLI requests.

A Heap-based Buffer Overflow vulnerability [CWE-122] vulnerability in Fortinet FortiClientWindows 7.4.0 through 7.4.3, FortiClientWindows 7.2.0 through 7.2.8 may allow an authenticated local IPSec user to execute arbitrary code or commands via "fortips74.sys". The attacker would need to bypass the Windows heap integrity protections

A Default Configuration vulnerability in FortiOS may allow an unauthenticated attacker on the same subnet to intercept sensitive information by impersonating the LDAP server.