PT-2026-65499 · Python · Cpython

Petr Viktorin · CVE-2026-6879 · Published 2026-07-28 · Updated 2026-07-28

Mitre

CVSS v4.0

2.0

Low

Base vector

AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Element.findall() and fully-consumed Element.iterfind() exhibit O(n^2) time complexity when using XPath index predicates (e.g. [1], [last()], [last()-N]) on XML documents with many same-tag siblings. Element.find() is only affected when the first match is near the end  of the sibling list, such as with [last()] or [last()-N];  .//item[1] short-circuits after the first match.

Fix

Weakness Enumeration

CWE-407

Related Identifiers

CVE-2026-6879

Affected Products

Cpython

References · 5

• https://github.com/python/cpython/commit/2ffab083782968a4d732738f4f1dff6bbd69d2b0 · Patch
• https://github.com/python/cpython/pull/152676 · Patch
• https://mail.python.org/archives/list/[e-mail]/thread/7YMZ6DDZVR26TJJBVO3RDNBAVGHNYAKR · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-6879 · Security Note
• https://github.com/python/cpython/issues/152674 · Note