High
Security advisory
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-44686
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 12:02 UTC · Revision 1
Source evidence
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.
osv:CVE-2021-44686
Complete source record
{
"id": "6bdc80966634c7954ccd61732189128ed3836ef88a58f6b4f3b3006f02b7a458",
"url": "https://osv.dev/vulnerability/CVE-2021-44686",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2021-44686",
"summary": "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.",
"evidence": "osv:CVE-2021-44686",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2021-44686",
"aliases": [
"CVE-2021-44686"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/kovidgoyal/calibre",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "f3ef3c85dd230b32d6955050111285ed82f04fef"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:calibre-ebook:calibre:*:*:*:*:*:*:*:*",
"range": [
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{
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}
],
"source": "CPE_RANGE"
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"database_specific": {
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}
}
],
"modified": "2026-10-20T10:55:06.773766048Z",
"provider": "osv",
"references": [
"https://lists.debian.org/debian-lts-announce/2024/09/msg00005.html",
"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/W7QKFPYJ23KG6WJ5NIYAM4N2NWZCLQGL/",
"https://bugs.launchpad.net/calibre/+bug/1951979",
"https://github.com/dwisiswant0/advisory/issues/18",
"https://github.com/kovidgoyal/calibre/compare/v5.31.1...v5.32.0"
],
"provider_metadata": {
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},
"related_cves": [
{
"value": "CVE-2021-44686",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 386909,
"published_at": "2021-12-07T00:15:08.087+00:00"
}