CVE-2026-118669: high-severity vulnerability in oauthlib
OAuthLib: Token grants can use attacker-supplied client_id for authorization after authenticating a different client
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.4epss 0.3%
OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. Prior to 4.0.0, the client_credentials and Resource Owner Password Credentials token grant handlers can authenticate request.client as one confidential client while retaining an attacker-supplied request.client_id for validate_grant_type and validate_scopes. A lower-privilege authenticated client can therefore cause grant and scope authorization to use another client's identity when an application validator relies on the documented client_id argument, potentially issuing tokens with unauthorized grants or scopes. Validators that authorize exclusively from request.client may not be affected. This issue is fixed in version 4.0.0.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N
Affected products
oauthlib · oauthlibRelated CVEs — oauthlib
In the same product, most dangerous first.
CVE-2022-36087MEDIUMOAuthLib vulnerable DoS when attacker provides malicious IPV6 URIEPSS 1.8%CVE-2026-49265MEDIUMOAuthLib: Timing Attack Vulnerability in PKCE code_verifier ComparisonEPSS 0.2%CVE-2026-49264MEDIUMOAuthLib: Unsafe JSONP callback injection in RevocationEndpoint allows arbitrary JavaScript response generationEPSS 0.2%CVE-2026-49272HIGHOAuthLib: Bearer token can be retrieved as long as client knows a valid client ID for device workflowEPSS —