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CVE-2026-1355VulnerabilityPublished Updated

CVE-2026-1355: GitHub Enterprise Server · Missing Authorization

Affects GitHub Enterprise ServerSource CVE Database V5

0

Not known to be exploited · CVSS 6.0 Medium · fixed in 3.19.2 : update GitHub Enterprise Server when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score
6.0Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.19.2
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Affected software

ProductAffectedFixed in
GitHubEnterprise ServerAffected
  • >=3.19.0 <3.19.2
  • >=3.18.0 <3.18.5
  • >=3.17.0 <3.17.11
  • >=3.16.0 <3.16.14
  • >=3.15.0 <3.15.18
  • >=3.14.0 <3.14.23
Fixed in–

AI-suggested

Organizations should immediately upgrade affected GitHub Enterprise Server instances to the patched versions (3.19.2 or later). Additionally, implement strict access controls and monitoring around repository migration operations to detect unusual upload activity. Enforce strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise. Audit and restrict user privileges to minimize the number of users with migration upload capabilities. Regularly review migration logs for unauthorized or suspicious actions. Consider implementing additional validation or integrity checks on migration archives before import to detect tampering. Educate administrators and developers about the risks of repository migration manipulation and encourage prompt patching of GitHub Enterprise Server deployments. Finally, maintain an incident response plan to address potential supply chain compromise scenarios.

Description

A Missing Authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to upload unauthorized content to another user’s repository migration export due to a missing authorization check in the repository migration upload endpoint. By supplying the migration identifier, an attacker could overwrite or replace a victim’s migration archive, potentially causing victims to download attacker-controlled repository data during migration restores or automated imports. An attacker would require authentication to the victim's GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.20 and was fixed in versions 3.19.2, 3.18.5, 3.17.11, 3.16.14, 3.15.18, 3.14.23. This vulnerability was reported via the GitHub Bug Bounty program.

References

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