Answer in brief
CVE-2026-126191 records a High severity (CVSS 7.5) vulnerability in Soup Sieve: Exponential ReDoS in selector compilation via \9-run in CSS_ESCAPES/IDENTIFIER. The current sources do not mark it as known exploited. The current feed maps facelessuser/soupsieve (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps facelessuser/soupsieve (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| facelessuser/soupsievegeneric | <3.0 | 3.0 |
Published upstream
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 12, 2026
Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 3.0, the CSS_ESCAPES and IDENTIFIER regular-expression subpatterns can backtrack exponentially on runs of ambiguous digit escapes in an attribute-name or tag position of an otherwise valid selector. The failure occurs during selector compilation through soupsieve.compile() or Beautiful Soup select() before SELECTOR_LIMIT is applied, so an application that accepts untrusted selector strings can have a worker stalled by a short input. This issue is fixed in version 3.0.
Quoted source text, attributed separately from HOL analysis.