CVE-2025-6998 Calibre Web 0.6.24 & Autocaliweb 0.7.0 - ReDoS
Unauthenticated attackers can cause denial of service in Calibre Web and Autocaliweb via a specially crafted username during login.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-6998?
CVE-2025-6998 is a high-severity denial of service vulnerability in Autocaliweb, published on 24 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
ReDoS in strip_whitespaces() function in cps/string_helper.py in Calibre Web and Autocaliweb allows unauthenticated remote attackers to cause denial of service via specially crafted username parameter that triggers catastrophic backtracking during login. This issue affects Calibre Web: 0.6.24 (Nicolette); Autocaliweb: from 0.7.0 before 0.7.1.
Weakness: CWE-1333
Which versions are affected by CVE-2025-6998?
3 open source packages ship an affected version, including calibreweb.
| Package | Affected | Fixed in |
|---|---|---|
calibreweb PyPI | All versions to 0.6.24 | None |
calibreweb PyPI | All versions to 0.6.24 | None |
calibreweb PyPI | All versions to 0.6.24 | None |
How do I fix CVE-2025-6998?
No fix has been published for CVE-2025-6998 yet. Limit exposure of the affected software until one is available.
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-2025-6998 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6998 exists.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-2g7m-ph9x-7q7m, PYSEC-2026-1228.