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CVE-2026-77987

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.17.21, 3.18.15, 3.19.12, 3.20.8, 3.21.6, and 1 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: total

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: total

  3. Record last updated

Affected versions

  • GitHub Enterprise Server

    From 3.17.0 · fixed in 3.17.21; From 3.18.0 · fixed in 3.18.15; From 3.19.0 · fixed in 3.19.12; From 3.20.0 · fixed in 3.20.8; From 3.21.0 · fixed in 3.21.6; From 3.22.0 · fixed in 3.22.1

References 6

docs.github.com