Which versions of Rocket.Chat are affected by EUVD-2026-39091?

Rocket.Chat's SAML single logout is vulnerable to unauthenticated remote session destruction attacks that can force-log out any SAML-authenticated user using only their email address.. A patch is available.

How to fix or mitigate EUVD-2026-39091?

Within 24 hours: Identify all Rocket.Chat instances in production and document current version numbers and release branches in use. Within 7 days: Apply vendor patches to all maintained release branches across production, staging, and development environments; test to confirm SAML functionality remains intact. Within 30 days: Audit SAML authentication logs for unauthorized logout patterns that indicate exploitation attempts and verify patch deployment across all systems.

Rocket.Chat EUVD-2026-39091

Q: What is the CVSS score of EUVD-2026-39091?

EUVD-2026-39091 has a CVSS 4.0 base score of 8.7 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.5%.

| CVE-2026-45677 HIGH

Missing Authorization (CWE-862)

2026-06-24 security-advisories@github.com

Authentication Bypass Google Microsoft

8.7

CVSS 4.0 · Vendor: github

Severity by source

Vendor (github) PRIMARY

8.7 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

7.5 HIGH

Remote, no auth and no interaction (PR:N/UI:N) to forge an unsigned logout; knowing an email NameID keeps AC:L; impact is session destruction only, so A:H with C:N/I:N.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Patch available

Jun 24, 2026 - 22:03 EUVD

Analysis Generated

Jun 24, 2026 - 21:37 vuln.today

CVE Published

Jun 24, 2026 - 21:16 cve.org

HIGH 8.7

DescriptionCVE.org

Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.0, 8.4.1, 8.3.3, 8.2.3, 8.1.4, 8.0.5, 7.13.7, and 7.10.11, Rocket.Chat's SAML integration does not verify the signature on inbound LogoutRequest messages. An unauthenticated remote attacker who knows a target user's SAML NameID - which major identity providers (Okta, Google Workspace, Microsoft Entra ID, JumpCloud) expose as the user's email address - can craft a valid-looking unsigned LogoutRequest and submit it to the SP logout endpoint. The server processes it as legitimate, immediately destroying the victim's session. Because the attack requires no authentication and no interaction from the victim, it can be repeated in a loop against individual users or scripted across many accounts, effectively rendering the Rocket.Chat instance unusable for SAML-authenticated users. This vulnerability is fixed in 8.5.0, 8.4.1, 8.3.3, 8.2.3, 8.1.4, 8.0.5, 7.13.7, and 7.10.11.

AnalysisAI

Session-destruction denial of service in Rocket.Chat's SAML single logout allows an unauthenticated remote attacker to forcibly log out any SAML-authenticated user by submitting a forged, unsigned LogoutRequest to the SP logout endpoint. Because the integration never validates the SAML signature, an attacker who knows only a victim's NameID - typically their email address, as exposed by Okta, Google Workspace, Microsoft Entra ID, and JumpCloud - can repeatedly destroy sessions and script the attack across many accounts to render the instance unusable. No public exploit identified at time of analysis; the CVSS 4.0 base score is 8.7 (availability-only impact), and fixes are available across all maintained release branches.

Technical ContextAI

The flaw lives in Rocket.Chat's SAML 2.0 Service Provider (SP) implementation, specifically its handling of inbound Single Logout (SLO) LogoutRequest messages. In a correct SAML SP, every assertion and logout message from the Identity Provider must carry an XML Digital Signature that the SP verifies against the IdP's trusted certificate; this signature is the only thing that distinguishes an IdP-originated message from an attacker-crafted one. Rocket.Chat omitted this verification on LogoutRequest, so any well-formed message naming a valid NameID is accepted as authoritative. This maps to CWE-862 (Missing Authorization): the server performs the session-destruction action without confirming that the requester is authorized (i.e., that the message genuinely came from the trusted IdP). The NameID used as the target identifier is, with the named major IdPs, the user's email address - a value that is generally public or easily enumerable, removing any practical secrecy barrier.

RemediationAI

Vendor-released patch: upgrade to the fixed version on your release branch - 8.5.0, 8.4.1, 8.3.3, 8.2.3, 8.1.4, 8.0.5, 7.13.7, or 7.10.11 - choosing the patched release closest to your current branch to minimize functional change. Full details are in the vendor advisory at https://github.com/RocketChat/Rocket.Chat/security/advisories/GHSA-pw6f-q8ww-vqfq. If you cannot patch immediately, the most direct compensating control is to restrict or block external access to the SAML SP single-logout (SLO) endpoint at a reverse proxy or WAF - for example, allow it only from your IdP's source ranges; the trade-off is that legitimate IdP-initiated logout from outside those ranges will break. Alternatively, disabling SAML single logout (if your deployment can tolerate it) prevents the forged-LogoutRequest path entirely, at the cost of losing coordinated single-sign-out behavior. Network-restricting Rocket.Chat to trusted users/VPN reduces the unauthenticated remote exposure but does not fix the underlying signature-verification gap, so patching remains mandatory.