CVE-2026-77987Critical· 9.8▾ MidnightA 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 reques…
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 53.9 · likelihood 0.2 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Sep 23.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.9%
Last analysed / modified upstream
9.3 → 9.8
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.
enterprise_server >= 3.17.0, < 3.17.21enterprise_server >= 3.18.0, < 3.18.15enterprise_server >= 3.19.0, < 3.19.12enterprise_server >= 3.20.0, < 3.20.8enterprise_server >= 3.21.0, < 3.21.6enterprise_server >= 3.22.0, < 3.22.1Upgrade past the affected range:
enterprise_server 3.22.1Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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