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TI-2026-54262 Aliases CVE-2026-77987GHSA-5p5v-w43x-q8v7

GitHub Enterprise Server notebook viewer vulnerable to Server-side request forgery

Priority MEDIUM 50CWE-208Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Information disclosure
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-208.

Summary

A server-side request forgery (SSRF) vulnerability was identified in the notebook viewer of GitHub Enterprise Server. The notebook viewer validated the scheme and host of a user-supplied URL but did not validate the port, allowing requests to be directed to internal services listening on other ports of the same appliance. Response bodies were not returned to the requester, but response timing acted as an oracle that allowed instance secrets to be extracted character by character. An extracted secret could then be used in a separate interaction with an internal service to obtain remote code execution on the appliance. Exploitation required network access to the instance and was unauthenticated when private mode was disabled, or required any authenticated user when private mode was enabled. This vulnerability affected GitHub Enterprise Server versions 3.17 through 3.22 and was fixed in versions 3.22.1, 3.21.6, 3.20.8, 3.19.12, 3.18.15, and 3.17.21. This vulnerability was reported through the GitHub Bug Bounty program.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00878 59th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
GitHubEnterprise Server3.17.0 and later; 3.18.0 and later; 3.19.0 and later; 3.20.0 and later; 3.21.0 and later; 3.22.0 and later—No fix listedCNA
  • Enterprise Server VendorGitHub Affected 3.17.0 and later; 3.18.0 and later; 3.19.0 and later; 3.20.0 and later; 3.21.0 and later; 3.22.0 and later Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*3.17.0 to before 3.17.21; 3.18.0 to before 3.18.15; 3.19.0 to before 3.19.12; 3.20.0 to before 3.20.8; 3.21.0 to before 3.21.6; 3.22.0 to before 3.22.1VulnerableGitHub
  • cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* Versions 3.17.0 to before 3.17.21; 3.18.0 to before 3.18.15; 3.19.0 to before 3.19.12; 3.20.0 to before 3.20.8; 3.21.0 to before 3.21.6; 3.22.0 to before 3.22.1 Vulnerable ·GitHub

Remediation

No fixed version listed by the sources yet.

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    GitHub Enterprise Server 3.17.*, 3.18.* and 4 more versions

    2 records Highest priority Priority MEDIUM 1 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2026-54240 Cross-site scripting in GitHub Enterprise ServerPriority LOW 34
    Show all 2 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-77987
  2. 2026-10-03 Alias added: GHSA-5p5v-w43x-q8v7

References

Advisory 6

  • TI-2024-04632 An authentication bypass vulnerability was present in the GitHub Enterprise Server (GHES)… CVSS 4.0CRITICAL 10.0
  • TI-2024-00181 Unsafe Reflection in Github Enterprise Server leading to Command Injection CVSS 3.1CRITICAL 9.8
  • TI-2024-00466 Privilege Escalation by Code Injection in the Management Console in GitHub Enterprise Server CVSS 3.1HIGH 8.8
  • TI-2026-03340 Remote code execution via git push option injection in GitHub Enterprise Server CVSS 4.0HIGH 8.7
  • TI-2024-08804 Improper signature verification in GitHub Enterprise Server CVSS 4.0CRITICAL 9.5
  • TI-2026-08177 Server-side request forgery in GitHub Enterprise Server CVSS 4.0CRITICAL 9.2
See all 125 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences