Github Enterprise Server <3.20 Missing Auth on Migration Upload Endpoint
CVE-2026-1355 Published on February 18, 2026
Missing Authorization Check in GitHub Enterprise Server Allows Unauthorized Uploads to Repository Migration Exports
A Missing Authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to upload unauthorized content to another users 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 victims 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.
Vulnerability Analysis
CVE-2026-1355 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
What is an AuthZ Vulnerability?
The software does not perform an authorization check when an actor attempts to access a resource or perform an action.
CVE-2026-1355 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-1355
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Affected Versions
GitHub Enterprise Server:- Version 3.19.0, <= 3.19.1 is affected.
- Version 3.18.0, <= 3.18.4 is affected.
- Version 3.17.0, <= 3.17.10 is affected.
- Version 3.16.0, <= 3.16.13 is affected.
- Version 3.15.0, <= 3.15.17 is affected.
- Version 3.14.0, <= 3.14.22 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.