CVE-2026-6879
Quadratic Behavior in xml.etree.ElementPath Index Predicates
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.
INFO
Published Date :
July 28, 2026, 3:17 p.m.
Last Modified :
July 28, 2026, 4:22 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-6879
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | LOW | 28c92f92-d60d-412d-b760-e73465c3df22 | ||||
| CVSS 4.0 | LOW | [email protected] |
Solution
- Refactor XPath expressions to avoid index predicates on large sibling sets.
- Use `.//tag[1]` to short-circuit after the first match.
- Consider alternative XML parsing methods if performance is critical.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6879.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6879 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6879
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6879 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-6879 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 28, 2026
Action Type Old Value New Value Added CWE CWE-407 Added SSVC {'id': 'CVE-2026-6879', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-28T14:49:33.309576Z'} -
New CVE Received by [email protected]
Jul. 28, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/python/cpython', 'vendor': 'Python Software Foundation', 'product': 'CPython', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.15.0', 'versionType': 'python'}], 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 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 Added Reference https://github.com/python/cpython/commit/2ffab083782968a4d732738f4f1dff6bbd69d2b0 Added Reference https://github.com/python/cpython/issues/152674 Added Reference https://github.com/python/cpython/pull/152676 Added Reference https://mail.python.org/archives/list/[email protected]/thread/7YMZ6DDZVR26TJJBVO3RDNBAVGHNYAKR/