PT-2021-24154 · Calibre+1 · Calibre+1

Dwisiswant0 · Published 2021-12-06 · Updated 2025-11-04 · CVE-2021-44686

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions: calibre versions prior to 5.32.0

Description: The issue is related to a regular expression in html preprocess rules within the ebooks/conversion/preprocess.py file that is vulnerable to ReDoS (Regular Expression Denial of Service). This could potentially lead to a denial of service.

Recommendations: For versions prior to 5.32.0, update to version 5.32.0 or later to resolve the issue. As a temporary workaround, consider restricting access to the html preprocess rules function in ebooks/conversion/preprocess.py until a patch is applied.

Exploit

Fix

DoS

Resource Exhaustion

Weakness Enumeration

CWE-400

Related Identifiers

ALT-PU-2021-3521

CVE-2021-44686

DLA-3862-1

MGASA-2021-0593

Affected Products

Alt Linux

Calibre

References · 20

• 🔥 https://github.com/dwisiswant0/advisory/issues/18 · Exploit
• 🔥 https://bugs.launchpad.net/calibre/+bug/1951979 · Exploit
• https://github.com/kovidgoyal/calibre/compare/v5.31.1...v5.32.0 · Patch
• https://ubuntu.com/security/CVE-2021-44686 · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/W7QKFPYJ23KG6WJ5NIYAM4N2NWZCLQGL · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-44686 · Security Note
• https://osv.dev/vulnerability/DLA-3862-1 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-44686 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-44686 · Vendor Advisory
• https://advisories.mageia.org/MGASA-2021-0593.html · Security Note
• https://osv.dev/vulnerability/CVE-2021-44686 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-44686 · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/[e-mail]/thread/W7QKFPYJ23KG6WJ5NIYAM4N2NWZCLQGL · Vendor Advisory
• https://osv.dev/vulnerability/MGASA-2021-0593 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-44686 · Vendor Advisory