CVE-2026-18730: CWE-918 Server-Side Request Forgery (SSRF) in GitHub Enterprise Server
Description
A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to cause the Manage API to send crafted outbound requests to an attacker-controlled host. An unauthenticated endpoint parsed an attacker-supplied cluster configuration and issued gateway-to-agent requests whose HMAC authenticated only a timestamp, not the request path or body. An attacker positioned to intercept the outbound request could capture this token and replay it against privileged management agent endpoints. High-availability deployments were not affected due to a topology restriction. This vulnerability affected GitHub Enterprise Server releases in the 3.17, 3.18, 3.19, 3.20, and 3.21 series and was fixed in versions 3.17.21, 3.18.15, 3.19.12, 3.20.8, and 3.21.6. This vulnerability was reported via the GitHub Bug Bounty program.
CVSS v4.0
Score 8.2high
Affected software
GitHub
Enterprise Server
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This SSRF vulnerability in GitHub Enterprise Server involves an unauthenticated endpoint that parses attacker-supplied cluster configurations and issues gateway-to-agent requests. The HMAC authentication used only a timestamp and did not cover the request path or body, allowing an attacker positioned to intercept outbound requests to capture and replay the token against privileged management agent endpoints. The flaw affects versions 3.17.0 up to but not including 3.17.21, 3.18.0 up to but not including 3.18.15, 3.19.0 up to but not including 3.19.12, 3.20.0 up to but not including 3.20.8, and 3.21.0 up to but not including 3.21.6. High-availability deployments are not vulnerable due to topology restrictions. The issue was responsibly disclosed via GitHub's Bug Bounty program and has been patched in the specified versions.
Potential Impact
An unauthenticated attacker could exploit this SSRF vulnerability to cause the GitHub Enterprise Server Manage API to send crafted requests to attacker-controlled hosts. By intercepting these outbound requests, the attacker could capture an HMAC token and replay it to access privileged management agent endpoints. This could lead to unauthorized actions within the management API context. High-availability deployments are not impacted due to topology restrictions. There are no known exploits in the wild at this time.
Mitigation Recommendations
This vulnerability has been fixed in GitHub Enterprise Server versions 3.17.21, 3.18.15, 3.19.12, 3.20.8, and 3.21.6. Users should upgrade to one of these fixed versions or later to remediate the issue. There is no indication that additional mitigation steps are required beyond applying the official patches.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_P
- Date Reserved
- 2026-08-03T18:33:43.917Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a974cb9acd9273b4942f39b
Added to database: 09/01/2026, 22:07:53 UTC
Last enriched: 09/23/2026, 02:06:17 UTC
Last updated: 10/16/2026, 06:48:15 UTC
Views: 152
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.