CVE-2026-75542

OAuth token exchange grants repository scopes for organizations the principal cannot access

HIGH
8.3
CVSS Score
Published: August 24, 2026 at 08:14 PM UTC
Updated: October 12, 2026 at 09:10 PM UTC
1 product affected across 1 vendorHexpm

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Severity
HIGH8.3
Exploit prediction
EPSS 0.5%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions2025-10-1871829cb6f6559bcceb1ef4e43a2fb8cdd3af654b
Vendor states this is fixed in bf0fb9d208f0acfabf7a2f7467c8231659e322a8 (fixed)
Affected range stops below 2026-08-24, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.3HIGHEEF
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-863

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