CVE-2026-106454 Twisted: IMAP wildcardToRegexp() ReDoS
An authenticated attacker can cause a denial of service in Twisted IMAP servers by sending malicious patterns that trigger catastrophic regex backtracking.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-106454?
CVE-2026-106454 is a medium-severity denial of service vulnerability in twisted, published on 6 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-1333
Which versions are affected by CVE-2026-106454?
3 open source packages ship an affected version, including twisted and Twisted.
| Package | Affected | Fixed in |
|---|---|---|
twisted PyPI | All versions to 25.5.0 | None |
twisted PyPI | All versions to 26.4.0 | None |
Twisted PyPI | All versions to 26.4.0 | None |
Linux distribution packages (1)
python-Twisted openSUSE:Tumbleweed | All versions | 26.4.0-4.1 |
How do I fix CVE-2026-106454?
No fix published yet.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-106454 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106454 exists.
Sources
Also known as AZL-106712, BELL-CVE-2026-106454, CLSA-2026-1791526134, DEBIAN-CVE-2026-106454, GHSA-8pqf-f4m5-798g, OESA-2026-4426 and 5 more.