Vulnerability · Published Jul 24, 2025 · Assigned by Fluid Attacks

CVE-2025-6998Calibre Web 0.6.24 & Autocaliweb 0.7.0 - ReDoS

High 8.7

In plain English

A high-severity regular-expression denial of service in Autocaliweb from Autocaliweb. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 62% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 4.0)8.7High

Exploit odds (30 days)1.0%top 38.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack tooling1Public PoC

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	calibreweb	no fix listed	GHSA-2g7m-ph9x-7q7m
PyPI	calibreweb	no fix listed	PYSEC-2026-1228

Affected products (as reported)

Vendor	Product	Versions
Calibre Web	Calibre Web	0.6.24
Autocaliweb	Autocaliweb	0.7.0 – before 0.7.1

Weakness: CWE-1333 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

https://fluidattacks.com/advisories/megadeth third-party-advisory
https://github.com/janeczku/calibre-web product
https://github.com/gelbphoenix/autocaliweb product