CVE-2026-6879

`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.

CVSS 4.0

2.0CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 28% of CVEs (scores of 2026-10-25)

CWE

CWE-407

Published

2026-07-28

Modified

2026-10-24

Record from

the NVD, synced 2026-10-24

References

• https://github.com/python/cpython/commit/02c08e6b747ac43d0d866a4ffa916bedf3423f81
• https://github.com/python/cpython/commit/037965c00a427cba5c05447efadc67c51a492e85
• https://github.com/python/cpython/commit/0583f24ae678993e3f7939f51ad5bcae5ad9dc70
• https://github.com/python/cpython/commit/2ffab083782968a4d732738f4f1dff6bbd69d2b0
• https://github.com/python/cpython/commit/390337b8ba1658833fdef379e1739c9f9533a8db

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