CVE-2026-21621

5.3 MEDIUM
Published: March 05, 2026 Modified: April 06, 2026
View on NVD

Description

Incorrect Authorization vulnerability in hexpm hexpm/hexpm ('Elixir.HexpmWeb.API.OAuthController' module) allows Privilege Escalation. An API key created with read-only permissions (domain: "api", resource: "read") can be escalated to full write access under specific conditions. When exchanging a read-only API key via the OAuth client_credentials grant, the resource qualifier is ignored. The resulting JWT receives the broad "api" scope instead of the expected "api:read" scope. This token is therefore treated as having full API access. If an attacker is able to obtain a victim's read-only API key and a valid 2FA (TOTP) code for the victim account, they can use the incorrectly scoped JWT to create a new full-access API key with unrestricted API permissions that does not expire by default and can perform write operations such as publishing, retiring, or modifying packages. This vulnerability is associated with program files lib/hexpm_web/controllers/api/oauth_controller.ex and program routines 'Elixir.HexpmWeb.API.OAuthController':validate_scopes_against_key/2. This issue affects hexpm: from 71829cb6f6559bcceb1ef4e43a2fb8cdd3af654b before 71c127afebb7ed7cc637eb231b98feb802d62999.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://cna.erlef.org/cves/CVE-2026-21621.html
Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
https://github.com/hexpm/hexpm/security/advisories/GHSA-739m-8727-j6w3
Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Mitigation Vendor Advisory
https://osv.dev/vulnerability/EEF-CVE-2026-21621
Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
5.3 / 10.0
EPSS (Exploit Probability)
0.0%
8th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

hex