What’s Vulnerable › Vulnerabilities

CVE-2026-49264: OAuthLib: Unsafe JSONP callback injection in RevocationEndpoint allows arbitrary JavaScript response generation

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-13 · updated 2026-10-16
• Weakness: CWE-79

Description

OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 0.6.1 until 4.0.0, OAuthLib's RevocationEndpoint in oauthlib/oauth2/rfc6749/endpoints/revocation.py reflects an unvalidated callback request parameter into success and error response bodies when enable_jsonp=True. The callback can come from the query string or request body and is used without restricting it to a legal JavaScript function name. A browser application that loads the revocation response as trusted JSONP and permits attacker influence over callback can therefore execute attacker-controlled JavaScript in the including application's origin, with access to its DOM and script-accessible data. The feature is disabled by default, so only deployments that explicitly enable JSONP are affected. This issue is fixed in version 4.0.0.

Affected products

• oauthlib: from 0.6.1, < 4.0.0

References

• https://github.com/oauthlib/oauthlib/commit/c888359f3c42bec235b2c5caab2069c9ed62457c
• https://github.com/oauthlib/oauthlib/pull/951
• https://github.com/oauthlib/oauthlib/releases/tag/v4.0.0
• https://github.com/oauthlib/oauthlib/security/advisories/GHSA-hj66-6f7g-4r5v
• https://github.com/oauthlib/oauthlib/security/advisories/GHSA-hj66-6f7g-4r5v

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