CVE-2026-3644

MEDIUM6.0

Incomplete control character validation in http.cookies

Published Mar 16, 2026

Modified 1 weeks ago

Details

The fix for CVE-2026-0672, which rejected control characters in http.cookies.Morsel, was incomplete. The Morsel.update(), |= operator, and unpickling paths were not patched, allowing control characters to bypass input validation. Additionally, BaseCookie.js_output() lacked the output validation applied to BaseCookie.output().

References

FIX

https://github.com/python/cpython/commit/57e88c1cf95e1481b94ae57abe1010469d47a6b4

FIX

https://github.com/python/cpython/commit/62ceb396fcbe69da1ded3702de586f4072b590dd

FIX

https://github.com/python/cpython/commit/d16ecc6c3626f0e2cc8f08c309c83934e8a979dd

WEB

https://github.com/python/cpython/issues/145599

FIX

https://github.com/python/cpython/pull/145600

ADVISORY