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Vulnerability · Published Nov 5, 2026 · Assigned by GitHub_M

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

High 8.5

In plain English

A high-severity improper authentication in oauthlib from oauthlib. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.5High
Exploit odds (30 days)0.3%top 74.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12python-oauthlibno fix listedDEBIAN-CVE-2026-49272
Debian:13python-oauthlibno fix listedDEBIAN-CVE-2026-49272
Debian:14python-oauthlibno fix listedDEBIAN-CVE-2026-49272
PyPIoauthlib4.0.1GHSA-3jp2-3mrg-2vxc
Ubuntu:22.04:LTSpython-oauthlibno fix listedUBUNTU-CVE-2026-49272
Ubuntu:24.04:LTSpython-oauthlibno fix listedUBUNTU-CVE-2026-49272
Ubuntu:26.04:LTSpython-oauthlibno fix listedUBUNTU-CVE-2026-49272
Ubuntu:26.10python-oauthlibno fix listedUBUNTU-CVE-2026-49272

Affected products (as reported)

VendorProductVersions
oauthlib oauthlib >= 3.3.0, < 4.0.1

Weakness: CWE-287 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:N

References