{"id":"CVE-2021-3449","published":"2021-03-25T14:25:13Z","modified":"2026-10-08T21:13:50Z","title":"NULL pointer deref in signature_algorithms processing","vendor":"OpenSSL","product":"OpenSSL","tier":"core","eol":null,"affectedVersions":[{"vendor":"OpenSSL","product":"OpenSSL","versions":["Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j)"]}],"description":{"text":"An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack. A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue. All OpenSSL 1.1.1 versions are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j).","provenance":"source","from":"CVE.org"},"summary":{"text":"A NULL pointer dereference in OpenSSL's signature_algorithms processing lets a TLS server be crashed by a maliciously crafted renegotiation ClientHello. An attacker needs only to send that message to a server running TLSv1.2 with renegotiation enabled (the default configuration), with no authentication or user interaction required; OpenSSL TLS clients are not affected.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T07:14:55Z"},"cvss":null,"epss":{"score":0.63542,"percentile":0.9921,"date":"2026-10-29","provenance":"source"},"kev":null,"vulncheckKev":null,"exploited":false,"otx":{"pulseCount":4,"pulses":[{"name":"ACTUALIZACION | IBM Cognos Analytics has addressed multiple vulnerabilities","url":"https://otx.alienvault.com/pulse/65da2e10a6bc9c007c0c0e32","created":"2024-02-24"},{"name":"Proof Point Emerging Exploit list","url":"https://otx.alienvault.com/pulse/6399fdc966948f6b537b9762","created":"2022-12-14"},{"name":"Siemens Releases June 2022 Patch Tuesday Advisories to Address 59 Bugs Affecting Its Products","url":"https://otx.alienvault.com/pulse/62ba972eb403bd2062972eaa","created":"2022-06-28"},{"name":"Oracle Critical Patch Update Advisory - April 2022","url":"https://otx.alienvault.com/pulse/626040216e00cd388b1b9180","created":"2022-04-20"}],"provenance":"machine"},"cwes":[],"references":[{"url":"https://www.openssl.org/news/secadv/20210325.txt","tags":[]},{"url":"https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=fb9fa6b51defd48157eeb207f52181f735d96148","tags":[]},{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-openssl-2021-GHY28dJd","tags":["vendor-advisory"]},{"url":"https://www.debian.org/security/2021/dsa-4875","tags":["vendor-advisory"]},{"url":"http://www.openwall.com/lists/oss-security/2021/03/27/1","tags":["mailing-list"]},{"url":"http://www.openwall.com/lists/oss-security/2021/03/27/2","tags":["mailing-list"]},{"url":"http://www.openwall.com/lists/oss-security/2021/03/28/3","tags":["mailing-list"]},{"url":"http://www.openwall.com/lists/oss-security/2021/03/28/4","tags":["mailing-list"]},{"url":"https://security.gentoo.org/glsa/202103-03","tags":["vendor-advisory"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCBFLLVQVILIVGZMBJL3IXZGKWQISYNP/","tags":["vendor-advisory"]},{"url":"https://www.oracle.com/security-alerts/cpuApr2021.html","tags":[]},{"url":"https://www.tenable.com/security/tns-2021-10","tags":[]},{"url":"https://www.tenable.com/security/tns-2021-09","tags":[]},{"url":"https://security.netapp.com/advisory/ntap-20210513-0002/","tags":[]},{"url":"https://security.netapp.com/advisory/ntap-20210326-0006/","tags":[]},{"url":"https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.asc","tags":[]},{"url":"https://www.tenable.com/security/tns-2021-06","tags":[]},{"url":"https://www.tenable.com/security/tns-2021-05","tags":[]},{"url":"https://kc.mcafee.com/corporate/index?page=content&id=SB10356","tags":[]},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","tags":[]},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-772220.pdf","tags":[]},{"url":"https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845","tags":[]},{"url":"https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013","tags":[]},{"url":"https://lists.debian.org/debian-lts-announce/2021/08/msg00029.html","tags":["mailing-list"]},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","tags":[]},{"url":"https://www.oracle.com/security-alerts/cpuapr2022.html","tags":[]},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf","tags":[]},{"url":"https://www.oracle.com/security-alerts/cpujul2022.html","tags":[]},{"url":"https://security.netapp.com/advisory/ntap-20240621-0006/","tags":[]}],"techniques":[],"reports":[],"affected":[{"ecosystem":"crates.io","package":"openssl-src","vulnerableRanges":["<111.15.0",">=0.0.0-0, <111.15.0"],"patched":["111.15.0"],"from":["GHSA-83mx-573x-5rw9","RUSTSEC-2021-0055"],"provenance":"source"}],"advisories":[{"id":"GHSA-83mx-573x-5rw9","url":"https://github.com/advisories/GHSA-83mx-573x-5rw9","severity":"MODERATE","ecosystem":"crates.io","package":"openssl-src","vulnerableRanges":["<111.15.0"],"patched":["111.15.0"],"provenance":"source","from":"GHSA"}],"euvd":{"id":"EUVD-2021-1628","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-1628","exploited":false,"exploitedSince":null,"provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":0,"earliest":"2021-03-26","earliestUrl":"https://github.com/riptl/cve-2021-3449","repos":[{"name":"riptl/cve-2021-3449","url":"https://github.com/riptl/cve-2021-3449","stars":224,"created":"2021-03-26"}]},"first":{"date":"2021-03-26","source":"PoC-in-GitHub","url":"https://github.com/riptl/cve-2021-3449"},"provenance":"source"},"exploitRefs":[],"flow":[],"timeline":[{"date":"2021-03-25","kind":"published","label":"Published (CVE.org)","url":"https://www.cve.org/CVERecord?id=CVE-2021-3449","provenance":"source"},{"date":"2021-03-26","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/riptl/cve-2021-3449","provenance":"source"}],"speed":{"daysToPublicExploit":1,"firstExploitFrom":"PoC-in-GitHub","daysToKev":null},"priority":{"score":26.4,"factors":[{"name":"In a KEV catalog","points":0.0,"detail":"not listed"},{"name":"Recent KEV listing","points":0.0,"detail":"not listed"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":19.84,"detail":"percentile 0.9921"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":5.0,"detail":"1 PoC-in-GitHub repo"},{"name":"Mentioned in OTX pulses","points":1.59,"detail":"4 pulses"},{"name":"CVSS severity","points":0.0,"detail":"no CVSS"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}