Coder up to 2.37.3 Identity Endpoint google-instance-identity authentication replay

Summaryinfo

A vulnerability was found in Coder up to 2.29.20/2.34.11/2.35.8/2.36.6/2.37.3. It has been classified as critical. This vulnerability affects unknown code of the file /api/v2/workspaceagents/google-instance-identity of the component Identity Endpoint. This manipulation causes authentication replay. This vulnerability is tracked as CVE-2026-118687. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical was found in Coder up to 2.29.20/2.34.11/2.35.8/2.36.6/2.37.3. Affected by this vulnerability is an unknown code block of the file /api/v2/workspaceagents/google-instance-identity of the component Identity Endpoint. The manipulation with an unknown input leads to a authentication replay vulnerability. The CWE definition for the vulnerability is CWE-294. A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes). As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Coder before 2.29.21, 2.30.0 before 2.34.12, 2.35.0 before 2.35.9, 2.36.0 before 2.36.7, and 2.37.0 before 2.37.4 does not validate the audience claim of GCE instance-identity JWTs at the POST /api/v2/workspaceagents/google-instance-identity endpoint. Attackers who obtain an unexpired format=full identity token minted for another relying party can replay it to obtain that workspace agent's session token, which remains valid until the workspace's next build.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-118687 since 10/28/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1040 according to MITRE ATT&CK.

Upgrading to version 2.29.21, 2.34.12, 2.35.9, 2.36.7 or 2.37.4 eliminates this vulnerability.

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Productinfo

Name

• Coder

Version

• 2.29.0
• 2.29.1
• 2.29.2
• 2.29.3
• 2.29.4
• 2.29.5
• 2.29.6
• 2.29.7
• 2.29.8
• 2.29.9
• 2.29.10
• 2.29.11
• 2.29.12
• 2.29.13
• 2.29.14
• 2.29.15
• 2.29.16
• 2.29.17
• 2.29.18
• 2.29.19
• 2.29.20
• 2.34.0
• 2.34.1
• 2.34.2
• 2.34.3
• 2.34.4
• 2.34.5
• 2.34.6
• 2.34.7
• 2.34.8
• 2.34.9
• 2.34.10
• 2.34.11
• 2.35.0
• 2.35.1
• 2.35.2
• 2.35.3
• 2.35.4
• 2.35.5
• 2.35.6
• 2.35.7
• 2.35.8
• 2.36.0
• 2.36.1
• 2.36.2
• 2.36.3
• 2.36.4
• 2.36.5
• 2.36.6
• 2.37.0
• 2.37.1
• 2.37.2
• 2.37.3

Website

• Product: https://github.com/coder/coder/

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