Quadratic Behavior in xml.etree.ElementPath Index Predicates
Summary
| CVE | CVE-2026-6879 |
|---|---|
| State | PUBLISHED |
| Assigner | PSF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-28 15:17:51 UTC |
| Updated | 2026-08-13 01:16:55 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 2 LOW from [email protected]
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.003550000 probability, percentile 0.285240000 (date 2026-08-14)
Problem Types: CWE-407 | CWE-407 CWE-407 Inefficient Algorithmic Complexity
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 2 | LOW | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 2 | LOW | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
HighAttack Requirements
PresentPrivileges Required
HighUser Interaction
PassiveConfidentiality
NoneIntegrity
NoneAvailability
LowSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Python Software Foundation | CPython | affected 3.10.21 python | Not specified |
| CNA | Python Software Foundation | CPython | affected 3.11.0 3.11.16 python | Not specified |
| CNA | Python Software Foundation | CPython | affected 3.12.0 3.12.14 python | Not specified |
| CNA | Python Software Foundation | CPython | affected 3.13.0 3.13.15 python | Not specified |
| CNA | Python Software Foundation | CPython | affected 3.14.0 3.14.7 python | Not specified |
| CNA | Python Software Foundation | CPython | affected 3.15.0a1 3.15.0rc1 python | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/python/cpython/commit/02c08e6b747ac43d0d866a4ffa916bedf3423f81 | [email protected] | github.com | |
| github.com/python/cpython/commit/0583f24ae678993e3f7939f51ad5bcae5ad9dc70 | [email protected] | github.com | |
| github.com/python/cpython/commit/2ffab083782968a4d732738f4f1dff6bbd69d2b0 | [email protected] | github.com | |
| github.com/python/cpython/commit/037965c00a427cba5c05447efadc67c51a492e85 | [email protected] | github.com | |
| github.com/python/cpython/commit/96510a3758f4a075f43223afdee3b6ee1a7a7f02 | [email protected] | github.com | |
| github.com/python/cpython/commit/cb409342a19f25656f62e679f8bac265fe1442c3 | [email protected] | github.com | |
| mail.python.org/archives/list/[email protected]/thread/7YMZ6DDZVR2... | [email protected] | mail.python.org | |
| github.com/python/cpython/pull/152676 | [email protected] | github.com | |
| github.com/python/cpython/commit/390337b8ba1658833fdef379e1739c9f9533a8db | [email protected] | github.com | |
| github.com/python/cpython/issues/152674 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: dm (https://github.com/DarkaMaul) (en)
CNA: Petr Viktorin (https://github.com/encukou) (en)
There are currently no legacy QID mappings associated with this CVE.