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4.3
CVE-2026-106454: Twisted IMAP list handling can freeze server
CVE-2026-106454 · published 29 days ago
Summary
The Twisted Python library lets email clients ask for mailbox lists. A flaw in how it processes certain search patterns can cause the server to stop responding while it works through the request. Update Twisted to a newer version as soon as a fix is released, or apply a temporary patch that validates client patterns before processing.
What to do
- Update debian twisted to version 26.4.0-5.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| – | twisted | twisted | <= 25.5.0 |
| pip | – | twisted |
<= 25.5.0 <= 26.4.0 |
| Debian:12 | debian | twisted | All versions |
| Ubuntu:Pro:14.04:LTS | canonical | twisted | All versions |
| Alpaquita:23 | bellsoft | py3-twisted | >= 22.10.0-r1 |
| Alpaquita:25 | bellsoft | py3-twisted | >= 24.11.0-r0 |
| Alpaquita:stream | bellsoft | py3-twisted | >= 22.10.0-r0 |
| Debian:14 | debian | twisted |
< 26.4.0-5 Fix: upgrade to 26.4.0-5
|
Original advisory text
Twisted: IMAP wildcardToRegexp() ReDoS
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.
References
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/106xxx/CVE-2026-1064... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-106454 Vendor Advisory
- https://github.com/advisories/GHSA-8pqf-f4m5-798g Vendor Advisory
- https://security-tracker.debian.org/tracker/CVE-2026-106454 Vendor Advisory
- https://github.com/twisted/twisted Product
- https://docs.bell-sw.com/security/cves/CVE-2026-106454 Vendor Advisory
- https://pypi.org/project/twisted Product
- https://github.com/twisted/twisted/security/advisories/GHSA-8pqf-f4m5-798g Third Party Advisory
- https://github.com/twisted/twisted/commit/2f8a3c29246f4eb324690e06a9767a11dc4aec... URL
- https://ubuntu.com/security/CVE-2026-106454 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-106454 Third Party Advisory
- https://github.com/twisted/twisted/pull/12788 Third Party Advisory
Internet-facing
60 days
Internal
At next upgrade
- Not known to be exploited
- Needs hands-on effort to exploit (estimated)
- Gives an attacker partial control (estimated)
Type
CWE-1333Inefficient Regular Expression Complexity (ReDoS)
Timeline
Published6 Oct 2026
Updated4 Nov 2026
First seen6 Oct 2026
Sources
CVE-2026-106454 · NVD
CVE-2026-106454 · MITRE
CVE-2026-106454 · OSV
GHSA-8pqf-f4m5-798g · GHSA
DEBIAN-CVE-2026-106454 · OSV
UBUNTU-CVE-2026-106454 · OSV
GHSA-8pqf-f4m5-798g · OSV
BELL-CVE-2026-106454 · OSV
PYSEC-2026-4304 · OSV
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