CVE-2026-6879

Description

`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.

References

https://mail.python.org/archives/list/[email protected]/thread/7YMZ6DDZVR26TJJBVO3RDNBAVGHNYAKR/

https://github.com/python/cpython/pull/152676

https://github.com/python/cpython/issues/152674

https://github.com/python/cpython/commit/2ffab083782968a4d732738f4f1dff6bbd69d2b0

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4