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TI-2026-68934 Aliases CVE-2026-106454GHSA-8pqf-f4m5-798g

Catastrophic regex backtracking in Twisted IMAP wildcard matching

Priority MEDIUM 53CWE-1333Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · Low
Fix status
Deferred Red Hat: fix deferred

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

Summary

Twisted versions 25.5.0 and earlier, and the PyPI package Twisted through 26.4.0, are affected. In the IMAP server, wildcardToRegexp() in twisted/mail/imap4.py passes other characters from LIST or LSUB patterns directly to re.compile() (CWE-1333). An authenticated user with low privileges can send an expensive pattern that causes catastrophic backtracking, and the single-threaded reactor then suspends all server input and output during the match.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

Twisted is an event-based framework for internet applications, supporting Python 3.6+. In 25.5.0 and earlier, wildcardToRegexp() in twisted/mail/imap4.py translates the IMAP asterisk and percent wildcards but passes all other characters from an authenticated client's LIST or LSUB pattern directly to re.compile(), allowing nested or otherwise expensive regular expression constructs to cause catastrophic backtracking when matched against mailbox names. Because Twisted uses a cooperative single-threaded reactor, the blocking match suspends all server input and output for the duration of the match. No fixed release is available as of this review.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00417 36th percentileScored 2026-11-07
Fix Deferred Red Hat: fix deferred

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
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
twistedtwistedup to 25.5.0—No fix listedCNA
—Twisted (PyPI)up to 26.4.0—No fix listedGHSA-8pqf-f4m5-798g
  • twisted Vendortwisted Affected up to 25.5.0 Fixed in — No fix listed CNA
  • Twisted (PyPI) Vendor— Affected up to 26.4.0 Fixed in — No fix listed GHSA-8pqf-f4m5-798g

Remediation

The sources list no fixed version for Twisted. Red Hat lists no available fix for Red Hat Ansible Automation Platform 2 and Red Hat OpenShift Container Platform 4, and no planned fix for Red Hat OpenStack Platform 16.2.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Ansible Automation Platform 2AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Red Hat OpenStack Platform 16.2AffectedNo fix planned: Out of support scope
Not affected: 1 product
  • Red Hat Hardened Images

Timeline

  1. 2026-10-06 Threatist record created from CVE-2026-106454
  2. 2026-10-07 Affected versions changed · Red Hat
  3. 2026-10-07 CVSS score added · Red Hat
  4. 2026-10-07 CISA SSVC decision points changed
  5. 2026-10-07 Priority changed: LOW → MEDIUM
  6. 2026-10-07 Alias added: GHSA-8pqf-f4m5-798g
  7. 2026-10-07 Affected versions changed · GHSA-8pqf-f4m5-798g
  8. 2026-10-07 CVSS score added · GHSA-8pqf-f4m5-798g
  9. 2026-10-07 Weakness changed · GHSA-8pqf-f4m5-798g
  10. 2026-10-07 5 new references · GHSA-8pqf-f4m5-798g
  11. 2026-10-16 Affected versions changed · GHSA-8pqf-f4m5-798g

References

Advisory 1

Other 4

  • TI-2026-79985 Unauthenticated memory exhaustion in Twisted domish XML parser CVSS 4.0HIGH 8.7
  • TI-2026-30612 Twisted: Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains CVSS 3.1HIGH 7.5
  • TI-2022-06090 Buffer Overflow in Twisted CVSS 3.1HIGH 7.5
  • TI-2024-27732 twisted.web has disordered HTTP pipeline response CVSS 3.1HIGH 8.3
  • TI-2024-27854 HTML injection in HTTP redirect body CVSS 3.1MEDIUM 6.1
  • TI-2026-79989 HTTP request smuggling in Twisted web via bare CR or LF in headers CVSS 3.1MEDIUM 5.4
See all 21 →

Sources

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