{"schemaVersion":3,"id":"CVE-2021-38496","aliases":["UBUNTU-CVE-2021-38496","DEBIAN-CVE-2021-38496"],"status":"published","duplicateOf":null,"title":null,"description":"During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.","dates":{"published":"2021-11-03T00:03:29.000Z","modified":"2024-08-04T01:44:23.406Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":8.8,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"OSV · Ubuntu","score":8.8,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","exploitability":7.2,"impact":9.8,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"OSV · Debian","score":8.8,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","exploitability":7.2,"impact":9.8,"computed":true},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":8.8,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":6.8,"severity":"medium","vector":"AV:N/AC:M/Au:N/C:P/I:P/A:P","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.01659,"percentile":0.76323,"severity":"low","asOf":"2026-10-20T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-20T00:00:00.000Z","baselineScore":0.01659},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.01645,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.01645,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.01645,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.01645,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.01659,"percentile":0.76323}],"last30":[{"date":"2026-09-20T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.01659,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.01659,"percentile":0.76323}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-416","name":"Use After Free","description":"The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory \"belongs\" to the code that operates on the new pointer.","type":"weakness","status":"Stable","abstraction":"Variant","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/416.html"}],"affected":[{"vendor":"debian","product":"firefox-esr","name":"firefox-esr","label":"firefox-esr","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/firefox-esr","purlType":"deb","versions":[{"text":"< 91.2.0esr-1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 91.2.0esr-1","eol":null,"hubHref":null},{"vendor":"debian","product":"thunderbird","name":"thunderbird","label":"thunderbird","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/thunderbird","purlType":"deb","versions":[{"text":"< 1:91.2.1-1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 1:91.2.1-1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"firefox","name":"firefox","label":"firefox","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/firefox","purlType":"deb","versions":[{"text":"< 93.0+build1-0ubuntu0.18.04.1","noFixRecorded":false,"fixedIn":null},{"text":"< 93.0+build1-0ubuntu0.20.04.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 93.0+build1-0ubuntu0.18.04.1 | < 93.0+build1-0ubuntu0.20.04.1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs38","name":"mozjs38","label":"mozjs38","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs38","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs52","name":"mozjs52","label":"mozjs52","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs52","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs68","name":"mozjs68","label":"mozjs68","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs68","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"mozjs78","name":"mozjs78","label":"mozjs78","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/mozjs78","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"thunderbird","name":"thunderbird","label":"thunderbird","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/thunderbird","purlType":"deb","versions":[{"text":"< 1:91.5.0+build1-0ubuntu0.18.04.1","noFixRecorded":false,"fixedIn":null},{"text":"< 1:91.5.0+build1-0ubuntu0.20.04.1","noFixRecorded":false,"fixedIn":null},{"text":"< 1:91.3.0+build2-0ubuntu1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 1:91.5.0+build1-0ubuntu0.18.04.1 | < 1:91.5.0+build1-0ubuntu0.20.04.1 | < 1:91.3.0+build2-0ubuntu1","eol":null,"hubHref":null},{"vendor":"debian","product":"debian_linux","name":"debian linux","label":"debian_linux","ecosystem":null,"cpePart":"o","purl":null,"purlType":null,"versions":[{"text":"9.0","noFixRecorded":false,"fixedIn":null},{"text":"10.0","noFixRecorded":false,"fixedIn":null},{"text":"11.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"9.0 | 10.0 | 11.0","eol":{"isEol":true,"eolDate":"2022-07-01T00:00:00.000Z","matchMethod":"cpe","cycle":{"name":"9","label":"9 (Stretch)","eolFrom":"2022-07-01T00:00:00.000Z","isLts":false,"isMaintained":true,"latestVersion":"9.13"},"product":{"name":"debian","label":"Debian","category":"os"}},"hubHref":"/vendor/debian/debian_linux"},{"vendor":"mozilla","product":"firefox","name":"Firefox","label":"firefox","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ unspecified, < 93","noFixRecorded":false,"fixedIn":null},{"text":"< 93.0","noFixRecorded":false,"fixedIn":null},{"text":"≥ 91.0, < 91.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ unspecified, < 93 | < 93.0 | ≥ 91.0, < 91.2","eol":{"isEol":null,"eolDate":null,"matchMethod":"cpe","cycle":null,"product":{"name":"firefox","label":"Firefox","category":"app"}},"hubHref":"/vendor/mozilla/firefox"},{"vendor":"mozilla","product":"firefox_esr","name":"firefox esr","label":"firefox_esr","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ unspecified, < 91.2","noFixRecorded":false,"fixedIn":null},{"text":"≥ unspecified, < 78.15","noFixRecorded":false,"fixedIn":null},{"text":"< 78.15","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ unspecified, < 91.2 | ≥ unspecified, < 78.15 | < 78.15","eol":null,"hubHref":"/vendor/mozilla/firefox_esr"},{"vendor":"mozilla","product":"thunderbird","name":"Thunderbird","label":"thunderbird","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ unspecified, < 78.15","noFixRecorded":false,"fixedIn":null},{"text":"≥ unspecified, < 91.2","noFixRecorded":false,"fixedIn":null},{"text":"< 78.15","noFixRecorded":false,"fixedIn":null},{"text":"≥ 91.0, < 91.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ unspecified, < 78.15 | ≥ unspecified, < 91.2 | < 78.15 | ≥ 91.0, < 91.2","eol":null,"hubHref":"/vendor/mozilla/thunderbird"}],"affectedCount":12,"eol":{"hasEol":true,"count":1},"references":[{"url":"https://www.mozilla.org/security/advisories/mfsa2021-47/","label":"www.mozilla.org/security/advisories/mfsa2021-47/","hostname":"www.mozilla.org","tags":["X Refsource MISC","Vendor Advisory"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-45/","label":"www.mozilla.org/security/advisories/mfsa2021-45/","hostname":"www.mozilla.org","tags":["X Refsource MISC","Vendor Advisory"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-43/","label":"www.mozilla.org/security/advisories/mfsa2021-43/","hostname":"www.mozilla.org","tags":["X Refsource MISC","Vendor Advisory"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-46/","label":"www.mozilla.org/security/advisories/mfsa2021-46/","hostname":"www.mozilla.org","tags":["X Refsource MISC","Broken Link"]},{"url":"https://www.mozilla.org/security/advisories/mfsa2021-44/","label":"www.mozilla.org/security/advisories/mfsa2021-44/","hostname":"www.mozilla.org","tags":["X Refsource MISC","Vendor Advisory"]},{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1725335","label":"bugzilla.mozilla.org/show_bug.cgi?id=1725335","hostname":"bugzilla.mozilla.org","tags":["X Refsource MISC","Issue Tracking","Permissions Required","Vendor Advisory"]},{"url":"https://www.debian.org/security/2022/dsa-5034","label":"www.debian.org/security/2022/dsa-5034","hostname":"www.debian.org","tags":["Vendor Advisory","X Refsource DEBIAN","Issue Tracking","Third Party Advisory"]},{"url":"https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html","label":"lists.debian.org/debian-lts-announce/2022/01/msg00001.html","hostname":"lists.debian.org","tags":["Mailing List","X Refsource MLIST","Third Party Advisory"]},{"url":"https://ubuntu.com/security/CVE-2021-38496","label":"ubuntu.com/security/CVE-2021-38496","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.mozilla.org/en-US/security/advisories/mfsa2021-43/#CVE-2021-38496","label":"www.mozilla.org/en-US/security/advisories/mfsa2021-43/","hostname":"www.mozilla.org","tags":["REPORT"]},{"url":"https://ubuntu.com/security/notices/USN-5132-1","label":"ubuntu.com/security/notices/USN-5132-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://ubuntu.com/security/notices/USN-5248-1","label":"ubuntu.com/security/notices/USN-5248-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://ubuntu.com/security/notices/USN-5107-1","label":"ubuntu.com/security/notices/USN-5107-1","hostname":"ubuntu.com","tags":["Advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-38496","label":"www.cve.org/CVERecord?id=CVE-2021-38496","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-38496","label":"security-tracker.debian.org/tracker/CVE-2021-38496","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":["DLA-2782-1","DLA-2874-1","DSA-4981-1","DSA-5034-1","MGASA-2021-0469","MGASA-2021-0478","OPENSUSE-SU-2021:1367-1","OPENSUSE-SU-2021:1635-1","OPENSUSE-SU-2021:3331-1","OPENSUSE-SU-2021:3451-1","OPENSUSE-SU-2021:4150-1","OPENSUSE-SU-2024:11570-1","OPENSUSE-SU-2024:11571-1","OPENSUSE-SU-2024:14572-1","RHSA-2021:3755","RHSA-2021:3756","RHSA-2021:3757","RHSA-2021:3791","RHSA-2021:3838","RHSA-2021:3839","RHSA-2021:3840","RHSA-2021:3841","SUSE-SU-2021:14826-1","SUSE-SU-2021:3331-1","SUSE-SU-2021:3446-1","SUSE-SU-2021:3451-1","SUSE-SU-2021:4150-1","USN-5107-1","USN-5248-1"],"duplicates":[],"related":["OPENSUSE-SU-2021:1367-1","OPENSUSE-SU-2021:1635-1","OPENSUSE-SU-2021:3331-1","OPENSUSE-SU-2021:3451-1","OPENSUSE-SU-2021:4150-1","OPENSUSE-SU-2024:11570-1","OPENSUSE-SU-2024:11571-1","OPENSUSE-SU-2024:14572-1","SUSE-SU-2021:14826-1","SUSE-SU-2021:3331-1","SUSE-SU-2021:3446-1","SUSE-SU-2021:3451-1","SUSE-SU-2021:4150-1","USN-5107-1","USN-5248-1"]},"timeline":[{"kind":"published","date":"2021-11-03T00:03:29.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2024-08-04T01:44:23.406Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":36,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T18:52:01.145Z","stale":false,"partial":false}}