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TI-2026-58860 Aliases CVE-2026-85999GHSA-j934-xhv5-fg8f

Regular expression denial of service in facelessuser soupsieve

Priority MEDIUM 63CWE-1333Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · Low
Fix status
Partial Red Hat: 1 fixed, 11 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-1333.

Summary

Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.9, selector_iter in src/soupsieve/css_parser.py trims the raw selector with RE_WS_END, an end-anchored WSC whitespace-and-comment expression used with search(), so the regular expression engine retries a greedy scan at every starting offset. An attacker-controlled valid selector containing a long internal whitespace run, or a selector containing a long CSS comment run followed by another token, causes quadratic CPU work before tokenization. User-controlled selectors can reach the path through soupsieve.compile() and BeautifulSoup.select(), while applications using only hard-coded selectors are unaffected. This root cause is separate from the IDENTIFIER and VALUE backtracking vulnerability because the cost occurs in RE_WS_END.search during trimming rather than token matching. The resulting CPU consumption can hold the Python GIL, exhaust workers, and stall a service without causing memory corruption or code execution. The issue is fixed in version 2.9.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00609 49th percentileScored 2026-11-07
Fix Partial soupsieve (facelessuser): 2.9soupsieve (PyPI): 2.9.0Red Hat: 1 advisoryRed Hat: 1 fixed, 11 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
facelessusersoupsievebefore 2.92.9Patch availableCNA
—soupsieve (PyPI)before 2.9.02.9.0Patch availableGHSA-j934-xhv5-fg8f
  • soupsieve Vendorfacelessuser Affected before 2.9 Fixed in 2.9 Patch available CNA
  • soupsieve (PyPI) Vendor— Affected before 2.9.0 Fixed in 2.9.0 Patch available GHSA-j934-xhv5-fg8f

Remediation

  • Fix · CNA soupsieve (facelessuser) Fixed in 2.9
  • Fix · GHSA-j934-xhv5-fg8f soupsieve (PyPI) Fixed in 2.9.0 Advisory →

Red Hat 1 advisory

  • RHSA-2026:84734 Released 2026-10-19 · Red Hat rating Critical
    RHOAI 3.4.5 - Red Hat OpenShift AI
    • Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-ai-gateway-payload-processing-rhel9, registry.redhat.io/rhoai/odh-automl-rhel9, registry.redhat.io/rhoai/odh-autorag-rhel9 +47

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Exploit IntelligenceAffectedNo fix yet
Lightspeed CoreAffectedNo fix yet: Fix deferred
Migration Toolkit for Applications 8AffectedNo fix yet: Fix deferred
OpenShift LightspeedAffectedNo fix yet: Fix deferred
Red Hat Ansible Automation Platform 2AffectedNo fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 5AffectedNo fix yet: Fix deferred
Red Hat OpenShift Virtualization 4AffectedNo fix yet: Fix deferred
Red Hat OpenStack Platform 17.1AffectedNo fix yet: Fix deferred
Red Hat Quay 3AffectedNo fix yet: Fix deferred
Red Hat OpenShift AI 3.4Fixed RHSA-2026:84734
Not affected: 2 products
  • Red Hat Hardened Images
  • Red Hat OpenShift AI 3.4

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-85999
  2. 2026-10-03 Alias added: GHSA-j934-xhv5-fg8f
  3. 2026-10-20 Fix available: RHSA-2026:84734 · Red Hat
  4. 2026-10-20 Fix available: Red Hat OpenShift AI 3.4 · Red Hat
  5. 2026-10-30 Affected versions changed · Red Hat

References

Advisory 1

Other 4

  • TI-2026-47703 pymdown-extensions: Exponential-backtracking ReDoS in caret, tilde, betterem, and magiclink inline processors CVSS 3.1HIGH 7.5
  • TI-2026-36631 Soup Sieve: Regular Expression Denial of Service (ReDoS) in soupsieve Selector Parser CVSS 3.1HIGH 7.5
  • TI-2026-36630 Soup Sieve: Memory Exhaustion via Large Comma-Separated Selector Lists in soupsieve CVSS 3.1HIGH 7.5
  • TI-2023-15603 Arbitrary file inclusion with the pymdowm-snippets extension CVSS 3.1HIGH 7.5
  • TI-2026-58861 Soup Sieve: Polynomial-time ReDoS (O(n²)) in the `IDENTIFIER` / `VALUE` selector sub-patterns CVSS 3.1MEDIUM 5.3
  • TI-2026-44140 PyMdown Extensions: Path traversal in the b64 extension lets <img src> read files outside base_path CVSS 3.1MEDIUM 5.3
See all 8 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences