calibre up to 5.31.x preprocess.py html_preprocess_rules incorrect regex

CVSS Meta Temp Score
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CTI Interest Score
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5.4$0-$5k0.00

Summaryinfo

A vulnerability classified as critical has been found in calibre up to 5.31.x. Impacted is the function html_preprocess_rules of the file ebooks/conversion/preprocess.py. Performing a manipulation results in incorrect regex. This vulnerability is cataloged as CVE-2021-44686. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in calibre up to 5.31.x. This affects the function html_preprocess_rules of the file ebooks/conversion/preprocess.py. The manipulation with an unknown input leads to a incorrect regex vulnerability. CWE is classifying the issue as CWE-185. The product specifies a regular expression in a way that causes data to be improperly matched or compared. This is going to have an impact on availability.

The weakness was shared 12/07/2021 as 18. It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2021-44686 since 12/06/2021. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 257996 (Linux Distros Unpatched Vulnerability : CVE-2021-44686), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.32.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (257996). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.4

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Incorrect regex
CWE: CWE-185 / CWE-697
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 257996
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-44686

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: calibre 5.32.0

Timelineinfo

12/06/2021 🔍
12/07/2021 +1 days 🔍
12/07/2021 +0 days 🔍
11/04/2025 +1428 days 🔍

Sourcesinfo

Advisory: 18
Status: Confirmed

CVE: CVE-2021-44686 (🔍)
GCVE (CVE): GCVE-0-2021-44686
GCVE (VulDB): GCVE-100-187599

Entryinfo

Created: 12/07/2021 07:42
Updated: 11/04/2025 21:08
Changes: 12/07/2021 07:42 (41), 12/09/2021 20:59 (1), 12/09/2021 21:06 (18), 08/28/2025 20:12 (16), 11/04/2025 21:08 (1)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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