Python up to 3.15.x CookieJar information disclosure

Summaryinfo

A vulnerability marked as problematic has been reported in Python up to 3.15.x. Affected is an unknown function of the component CookieJar. The manipulation leads to information disclosure. This vulnerability is uniquely identified as CVE-2026-124249. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Python up to 3.15.x and classified as problematic. This issue affects an unknown code of the component CookieJar. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. The summary by CVE is:

http.cookiejar.CookieJar deleted a stored cookie when a response carried an already expired Set-Cookie header for it, using the Domain and Path attributes from the header without consulting the cookie policy. A server could therefore delete cookies belonging to other domains from a shared cookie jar, such as the one used by urllib's HTTPCookieProcessor. The fix consults the cookie policy before an expired cookie may delete an existing one, as required by RFC 6265 section 5.3.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-124249 since 11/07/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1592 for this issue.

Upgrading to version 3.16.0 eliminates this vulnerability.

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Productinfo

Type

• Programming Language Software

Name

• Python

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13
• 3.14
• 3.15

License

• open-source

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CPE 2.2info

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