# 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.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 7 Oct 2026
- **Also known as:** AZL-106712, BELL-CVE-2026-106454, CLSA-2026-1791526134, DEBIAN-CVE-2026-106454, GHSA-8pqf-f4m5-798g, OESA-2026-4426, OESA-2026-4427, OESA-2026-4428, PYSEC-2026-4304, UBUNTU-CVE-2026-106454, openSUSE-SU-2026:12137-1

## 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 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2026-106454?

3 open source packages ship an affected version, including twisted and Twisted.


| Package | Ecosystem | 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 |
| `python-Twisted` | openSUSE:Tumbleweed | All versions | 26.4.0-4.1 |

## How do I fix CVE-2026-106454?

No fix published yet.

## Is CVE-2026-106454 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106454 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-106454 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106454 exists.

Affected packages and fixed versions:
- twisted (PyPI): affected all versions up to 25.5.0; no fix listed
- twisted (PyPI): affected all versions up to 26.4.0; no fix listed
- Twisted (PyPI): affected all versions up to 26.4.0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-106454/ (Markdown: https://insights.sbomify.com/CVE-2026-106454/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-106454
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-106454
- OSV: https://osv.dev/vulnerability/CVE-2026-106454

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-106454/
Summaries are generated and may contain mistakes; the official description above is the record.