CVE-2026-21621

7.0 HIGH 0.4% exploit odds Fix listed Auth & access Library

What it is

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.

At a glance

Exploitability: Can be exploited over the network with a low-privilege account. High risk of data tampering.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-03-05 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 10:18 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 7.0 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-03-05 20:16 UTC
Last modified: 2026-06-17 10:18 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-863 · Incorrect authorization
Record status: Modified

Affected

Hex Hexpm < 2026-03-05

Attack profile CVSS 4.0 · 7.0

Attack vector: Network
Complexity: Low
Attack requirements: Present
Privileges needed: Low
User interaction: None
Confidentiality: None
Integrity: High
Availability: Low

Raw vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-21621.md and follow it. Check whether this project is affected by CVE-2026-21621. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record