---
id: CVE-2026-126193
title: >-
  Soup Sieve: Uncontrolled recursion in Soup Sieve CSS parser lets nested
  pseudo-class selectors exhaust the Python call stack
summary: "Soup Sieve is a CSS selector library for Beautiful Soup. From 0.4 until 3.0, deeply nested CSS pseudo-class selectors can cause recursive parsing to exceed Python’s recursion limit and raise \_RecursionError\_. Applications accepting untru…"
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cvssSource: cna
cwe:
  - CWE-674
vendor: facelessuser
product: soupsieve
affected:
  - 'soupsieve >= 0.4, < 3.0'
published: '2026-11-12'
updated: '2026-11-12'
sourceUpdated: '2026-11-12T17:12:02.083Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-126193'
references:
  - url: >-
      https://github.com/facelessuser/soupsieve/security/advisories/GHSA-7g44-g9rc-x53w
    label: >-
      https://github.com/facelessuser/soupsieve/security/advisories/GHSA-7g44-g9rc-x53w
  - url: 'https://github.com/facelessuser/soupsieve/pull/306'
    label: 'https://github.com/facelessuser/soupsieve/pull/306'
  - url: >-
      https://github.com/facelessuser/soupsieve/commit/52de12f157a373614ad0f486d434551c5a4378ee
    label: >-
      https://github.com/facelessuser/soupsieve/commit/52de12f157a373614ad0f486d434551c5a4378ee
  - url: 'https://github.com/facelessuser/soupsieve/releases/tag/3.0'
    label: 'https://github.com/facelessuser/soupsieve/releases/tag/3.0'
tags:
  - cve.org
ingestedAt: '2026-11-12T17:51:14.491Z'
---

## Overview

Soup Sieve is a CSS selector library for Beautiful Soup. From 0.4 until 3.0, deeply nested CSS pseudo-class selectors can cause recursive parsing to exceed Python’s recursion limit and raise  RecursionError . Applications accepting untrusted selectors may experience failure of the affected request or task if the exception is not handled. The demonstrated behavior is recoverable and does not establish an interpreter crash or persistent service-wide denial of service. This vulnerability is fixed in version 3.0.

## Affected

- `soupsieve >= 0.4, < 3.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.