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CVE-2021-44686

Published: Dec 6, 2021Updated: Nov 4, 2025 Sources: CVE List NVDCWE-400
NVD MITRE
7.5CVSSHIGH
EPSS Score
5.0%
Top 8.9%
CISA KEV
Not in KEV
Exploits
2 Known
Remediation
Patch Available

Description

calibre before 5.32.0 contains a regular expression that is vulnerable to ReDoS (Regular Expression Denial of Service) in html_preprocess_rules in ebooks/conversion/preprocess.py.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-400

Affected Products

n/an/a
calibrecalibre-ebook
On-prem
Consumer Software / productivity
fedorafedoraproject
On-premOS
Operating Systems / linux-distro
calibre-ebookoss-projectConsumer Softwareaka calibre
fedoraprojectoss-projectUSOperating Systemsaka fedora project

Attack Graph

Products CVE Techniques Tactics

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Exploitability

2 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://bugs.launchpad.net/calibre/+bug/1951979
bugs.launchpad.net
https://github.com/dwisiswant0/advisory/issues/18
github.com
https://github.com/kovidgoyal/calibre/compare/v5.31.1...v5.32.0
github.com
and 2 more references View all →

Timeline

Published
Dec 6, 2021
Last Updated
Nov 4, 2025

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