{"id":"UBUNTU-CVE-2021-44686","details":"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.","modified":"2026-05-20T16:06:30.589964198Z","published":"2021-12-07T00:15:00Z","upstream":["CVE-2021-44686"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-44686"},{"type":"REPORT","url":"https://bugs.launchpad.net/calibre/+bug/1951979"},{"type":"REPORT","url":"https://github.com/dwisiswant0/advisory/issues/18"},{"type":"REPORT","url":"https://github.com/kovidgoyal/calibre/compare/v5.31.1...v5.32.0"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-44686"}],"affected":[{"package":{"name":"calibre","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/calibre?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.33.0+dfsg-1build1","2.38.0+dfsg-1","2.45.0+dfsg-1","2.45.0+dfsg-1build1","2.48.0+dfsg-1","2.48.0+dfsg-1build1","2.54.0+dfsg-1","2.55.0+dfsg-1","2.55.0+dfsg-1ubuntu0.2"],"ecosystem_specific":{"binaries":[{"binary_version":"2.55.0+dfsg-1ubuntu0.2","binary_name":"calibre"},{"binary_version":"2.55.0+dfsg-1ubuntu0.2","binary_name":"calibre-bin"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-44686.json"}},{"package":{"name":"calibre","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/calibre?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.7.0+dfsg-2","3.7.0+dfsg-2build1","3.12.0+dfsg-1","3.13.0+dfsg-1","3.14.0+dfsg-1","3.15.0.1+dfsg-1","3.16.0+dfsg-1","3.16.0+dfsg-1build1","3.17.0+dfsg-1","3.17.0+dfsg-2","3.18.0+dfsg-1build1","3.19.0+dfsg-1","3.20.0+dfsg-1","3.21.0+dfsg-1","3.21.0+dfsg-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"calibre","binary_version":"3.21.0+dfsg-1build1"},{"binary_name":"calibre-bin","binary_version":"3.21.0+dfsg-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-44686.json"}},{"package":{"name":"calibre","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/calibre?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.46.0+dfsg-1","4.2.0+dfsg-2","4.3.0+dfsg-1","4.3.0+dfsg-2","4.4.0+dfsg-1","4.5.0+dfsg-1","4.5.0+dfsg-2","4.5.0+dfsg-3","4.6.0+dfsg-1","4.7.0+dfsg-1","4.99.3+dfsg-2","4.99.4+dfsg-1","4.99.4+dfsg-1build1","4.99.4+dfsg+really4.10.0+py3-2","4.99.4+dfsg+really4.11.2-1","4.99.4+dfsg+really4.11.2-1build1","4.99.4+dfsg+really4.12.0-1","4.99.4+dfsg+really4.12.0-1build1","4.99.4+dfsg+really4.12.0-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"calibre","binary_version":"4.99.4+dfsg+really4.12.0-1ubuntu1"},{"binary_name":"calibre-bin","binary_version":"4.99.4+dfsg+really4.12.0-1ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-44686.json"}},{"package":{"name":"calibre","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/calibre?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.25.0+dfsg-2","5.33.2+dfsg-1","5.34.0+dfsg-1","5.35.0+dfsg-1ubuntu2","5.37.0+dfsg-1","5.37.0+dfsg-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"calibre","binary_version":"5.37.0+dfsg-1build1"},{"binary_name":"calibre-bin","binary_version":"5.37.0+dfsg-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-44686.json"}},{"package":{"name":"calibre","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/calibre?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["8.8.0+ds-3build1","8.13.0+ds+~0.10.5-3","8.14.0+ds+~0.10.5-1","8.15.0+ds+~0.10.5-1","8.16.0+ds+~0.10.5-2","8.16.2+ds+~0.10.5-1","8.16.2+ds+~0.10.5-2","8.16.2+ds+~0.10.5-3","9.2.1+ds+~0.10.5-2build1"],"ecosystem_specific":{"binaries":[{"binary_version":"9.2.1+ds+~0.10.5-2build1","binary_name":"calibre"},{"binary_name":"calibre-bin","binary_version":"9.2.1+ds+~0.10.5-2build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-44686.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"low"}]}