# CVE-2026-49272: OAuthLib: Bearer token can be retrieved as long as client knows a valid client ID for device workflow

Status: published. Published: 2026-11-05. Updated: 2026-11-05.

OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.3.0 until 4.0.1, OAuthLib's RFC 8628 device workflow does not require DeviceCodeGrant.validate_token_request to check that the device_code parameter is present and valid. A caller whose client request is accepted by the configured validator and who knows a valid client ID enabled for the device workflow can submit a missing or bogus device code to the token endpoint and obtain a bearer token without completing device authorization. This issue is fixed in version 4.0.1.

## Remediation

- fix: oauthlib (PyPI): OSV reports a fixed version 4.0.0. Check the advisory for supported release branches. (source: OSV GHSA-3jp2-3mrg-2vxc) — https://github.com/advisories/GHSA-3jp2-3mrg-2vxc

## Affected products and versions

- oauthlib / oauthlib: >= 3.3.0, < 4.0.1 (affected). Source: CNA: GitHub_M
-  / oauthlib (oauthlib): 3.3.0 (affected, PyPI); 3.3.1 (affected, PyPI); Ecosystem version events: introduced 3.3.0; fixed 4.0.0. Source: OSV GHSA-3jp2-3mrg-2vxc

## Severity and prioritization

- CVSS 3.1: 8.5 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-287

## Exploit evidence

- exploit: https://github.com/oauthlib/oauthlib/security/advisories/GHSA-3jp2-3mrg-2vxc (ADP: CISA-ADP)

## References

- https://github.com/oauthlib/oauthlib/security/advisories/GHSA-3jp2-3mrg-2vxc (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/oauthlib/oauthlib/pull/954 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/oauthlib/oauthlib/commit/77a5f1c8ce00da2b0b8c5f6e9cc129920085f114 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/oauthlib/oauthlib/releases/tag/v4.0.1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/oauthlib/oauthlib/security/advisories/GHSA-3jp2-3mrg-2vxc (ADP: CISA-ADP; exploit)

- https://github.com/advisories/GHSA-3jp2-3mrg-2vxc (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-3jp2-3mrg-2vxc (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-49272; retrieved 2026-11-05; source updated 2026-11-05

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-3jp2-3mrg-2vxc; retrieved 2026-11-05; source updated 2026-10-27

Revision: c388533fae7ff426d1b6aec83cca7087b043e5cd735b5c282dc9bba95f03ebd2

Canonical: https://y2.dev/cve/CVE-2026-49272

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