EUVD Vulnerability Catalog

EUVD-2026-84872

Severity: CRITICAL Base Score: 9.3 CVSS Version: 4.0

Vulnerability Description

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.

CVSS Vector Analysis

Below is the complete, human-readable breakdown of the CVSS metric string: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

▪ Attack Vector (AV): Network
▪ Attack Complexity (AC): Low
▪ Attack Requirements (AT): None
▪ Privileges Required (PR): None
▪ User Interaction (UI): None
▪ Vulnerability Confidentiality Impact (VC): High
▪ Vulnerability Integrity Impact (VI): High
▪ Vulnerability Availability Impact (VA): High
▪ Subsequent Confidentiality Impact (SC): None
▪ Subsequent Integrity Impact (SI): None
▪ Subsequent Availability Impact (SA): None

Affected Vendors & Systems

Vendor GitHub

References & Advisory Links

Metadata Profile

Database Authority

European Union Agency for Cybersecurity (ENISA) EUVD

Assigner

GitHub_P

EPSS Probability

0

Known Aliases
CVE-2026-77987
Published On

2026-09-22

Last Updated

2026-09-22