{"api_version":"1","generated_at":"2026-04-23T09:39:09+00:00","cve":"CVE-2019-12521","urls":{"html":"https://cve.report/CVE-2019-12521","api":"https://cve.report/api/cve/CVE-2019-12521.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2019-12521","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2019-12521"},"summary":{"title":"CVE-2019-12521","description":"An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.","state":"PUBLIC","assigner":"cve@mitre.org","published_at":"2020-04-15 19:15:00","updated_at":"2021-07-21 11:39:00"},"problem_types":["CWE-787","CWE-193"],"metrics":[],"references":[{"url":"https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html","name":"[debian-lts-announce] 20200710 [SECURITY] [DLA 2278-1] squid3 security update","refsource":"MLIST","tags":["Mailing List","Third Party Advisory"],"title":"[SECURITY] [DLA 2278-1] squid3 security update","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://security.netapp.com/advisory/ntap-20210205-0006/","name":"https://security.netapp.com/advisory/ntap-20210205-0006/","refsource":"CONFIRM","tags":["Third Party Advisory"],"title":"January 2021 Squid Vulnerabilities in NetApp Products | NetApp Product Security","mime":"text/html","httpstatus":"200","archivestatus":"0"},{"url":"https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12521.txt","name":"https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12521.txt","refsource":"MISC","tags":["Third Party Advisory"],"title":"squid/CVEs/CVE-2019-12521.txt · master · Jeriko One / Security · GitLab","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00018.html","name":"openSUSE-SU-2020:0623","refsource":"SUSE","tags":["Mailing List","Third Party Advisory"],"title":"[security-announce] openSUSE-SU-2020:0623-1: important: Security update","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://security.gentoo.org/glsa/202005-05","name":"GLSA-202005-05","refsource":"GENTOO","tags":["Third Party Advisory"],"title":"Squid: Multiple vulnerabilities (GLSA 202005-05) — Gentoo security","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://www.debian.org/security/2020/dsa-4682","name":"DSA-4682","refsource":"DEBIAN","tags":["Third Party Advisory"],"title":"Debian -- Security Information -- DSA-4682-1 squid","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://usn.ubuntu.com/4356-1/","name":"USN-4356-1","refsource":"UBUNTU","tags":["Third Party Advisory"],"title":"USN-4356-1: Squid vulnerabilities | Ubuntu security notices | Ubuntu","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"http://www.openwall.com/lists/oss-security/2020/04/23/1","name":"[oss-security] 20200423 [ADVISORY] SQUID-2019:12 Multiple issues in ESI Response processing","refsource":"MLIST","tags":["Mailing List","Patch","Third Party Advisory"],"title":"oss-security - [ADVISORY] SQUID-2019:12 Multiple issues in ESI Response processing","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://www.cve.org/CVERecord?id=CVE-2019-12521","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2019-12521","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"16.04","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"lts","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"18.04","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"lts","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"19.10","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"20.04","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"lts","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"1","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"16.04","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"lts","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"1","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"18.04","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"lts","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"1","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"19.10","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"1","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"canonical","cpe5":"ubuntu_linux","cpe6":"20.04","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"lts","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"debian","cpe5":"debian_linux","cpe6":"10.0","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"debian","cpe5":"debian_linux","cpe6":"9.0","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"1","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"debian","cpe5":"debian_linux","cpe6":"10.0","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"1","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"debian","cpe5":"debian_linux","cpe6":"9.0","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"opensuse","cpe5":"leap","cpe6":"15.1","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"1","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"opensuse","cpe5":"leap","cpe6":"15.1","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"3.5.28","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"squid-cache","cpe5":"squid","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"4.7","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"squid-cache","cpe5":"squid","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2019","cve_id":"12521","vulnerable":"1","versionEndIncluding":"5.0.1","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"squid-cache","cpe5":"squid","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[{"cve":"CVE-2019-12521","qid":"159658","title":"Oracle Enterprise Linux Security Update for squid:4 (ELSA-2020-4743)"},{"cve":"CVE-2019-12521","qid":"296074","title":"Oracle Solaris 11.4 Support Repository Update (SRU) 22.69.4 Missing (CPUAPR2020)"},{"cve":"CVE-2019-12521","qid":"356292","title":"Amazon Linux Security Advisory for squid : ALASSQUID4-2023-008"},{"cve":"CVE-2019-12521","qid":"357357","title":"Amazon Linux Security Advisory for squid : ALAS2-2024-2509"},{"cve":"CVE-2019-12521","qid":"377360","title":"Alibaba Cloud Linux Security Update for squid:4 (ALINUX3-SA-2022:0124)"},{"cve":"CVE-2019-12521","qid":"940034","title":"AlmaLinux Security Update for squid:4 (ALSA-2020:4743)"},{"cve":"CVE-2019-12521","qid":"960867","title":"Rocky Linux Security Update for squid:4 (RLSA-2020:4743)"}]},"source_records":{"cve_program":{"CVE_data_meta":{"ASSIGNER":"cve@mitre.org","ID":"CVE-2019-12521","STATE":"PUBLIC"},"affects":{"vendor":{"vendor_data":[{"product":{"product_data":[{"product_name":"n/a","version":{"version_data":[{"version_value":"n/a"}]}}]},"vendor_name":"n/a"}]}},"data_format":"MITRE","data_type":"CVE","data_version":"4.0","description":{"description_data":[{"lang":"eng","value":"An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing."}]},"problemtype":{"problemtype_data":[{"description":[{"lang":"eng","value":"n/a"}]}]},"references":{"reference_data":[{"refsource":"MISC","name":"https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12521.txt","url":"https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12521.txt"},{"refsource":"MLIST","name":"[oss-security] 20200423 [ADVISORY] SQUID-2019:12 Multiple issues in ESI Response processing","url":"http://www.openwall.com/lists/oss-security/2020/04/23/1"},{"refsource":"DEBIAN","name":"DSA-4682","url":"https://www.debian.org/security/2020/dsa-4682"},{"refsource":"SUSE","name":"openSUSE-SU-2020:0623","url":"http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00018.html"},{"refsource":"GENTOO","name":"GLSA-202005-05","url":"https://security.gentoo.org/glsa/202005-05"},{"refsource":"UBUNTU","name":"USN-4356-1","url":"https://usn.ubuntu.com/4356-1/"},{"refsource":"MLIST","name":"[debian-lts-announce] 20200710 [SECURITY] [DLA 2278-1] squid3 security update","url":"https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html"},{"refsource":"CONFIRM","name":"https://security.netapp.com/advisory/ntap-20210205-0006/","url":"https://security.netapp.com/advisory/ntap-20210205-0006/"}]}},"nvd":{"publishedDate":"2020-04-15 19:15:00","lastModifiedDate":"2021-07-21 11:39:00","problem_types":["CWE-787","CWE-193"],"metrics":{"baseMetricV3":{"cvssV3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH","baseScore":5.9,"baseSeverity":"MEDIUM"},"exploitabilityScore":2.2,"impactScore":3.6},"baseMetricV2":{"cvssV2":{"version":"2.0","vectorString":"AV:N/AC:M/Au:N/C:N/I:N/A:P","accessVector":"NETWORK","accessComplexity":"MEDIUM","authentication":"NONE","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"PARTIAL","baseScore":4.3},"severity":"MEDIUM","exploitabilityScore":8.6,"impactScore":2.9,"acInsufInfo":false,"obtainAllPrivilege":false,"obtainUserPrivilege":false,"obtainOtherPrivilege":false,"userInteractionRequired":false}},"configurations":{"CVE_data_version":"4.0","nodes":[{"operator":"OR","children":[],"cpe_match":[{"vulnerable":true,"cpe23Uri":"cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*","versionStartIncluding":"3.0","versionEndIncluding":"3.5.28","cpe_name":[]},{"vulnerable":true,"cpe23Uri":"cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*","versionStartIncluding":"4.0","versionEndIncluding":"4.7","cpe_name":[]},{"vulnerable":true,"cpe23Uri":"cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*","versionStartIncluding":"5.0","versionEndIncluding":"5.0.1","cpe_name":[]}]},{"operator":"OR","children":[],"cpe_match":[{"vulnerable":true,"cpe23Uri":"cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*","cpe_name":[]},{"vulnerable":true,"cpe23Uri":"cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*","cpe_name":[]},{"vulnerable":true,"cpe23Uri":"cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*","cpe_name":[]},{"vulnerable":true,"cpe23Uri":"cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*","cpe_name":[]}]},{"operator":"OR","children":[],"cpe_match":[{"vulnerable":true,"cpe23Uri":"cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*","cpe_name":[]},{"vulnerable":true,"cpe23Uri":"cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*","cpe_name":[]}]},{"operator":"OR","children":[],"cpe_match":[{"vulnerable":true,"cpe23Uri":"cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*","cpe_name":[]}]}]}},"legacy_mitre":{"record":{"CveYear":"2019","CveId":"12521","Ordinal":"150859","Title":"CVE-2019-12521","CVE":"CVE-2019-12521","Year":"2019"},"notes":[{"CveYear":"2019","CveId":"12521","Ordinal":"1","NoteData":"An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.","Type":"Description","Title":null},{"CveYear":"2019","CveId":"12521","Ordinal":"2","NoteData":"2020-04-15","Type":"Other","Title":"Published"},{"CveYear":"2019","CveId":"12521","Ordinal":"3","NoteData":"2021-02-05","Type":"Other","Title":"Modified"}]}}}