Description
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).
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| OpenSSL | OpenSSL | Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j) | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openssl | 1.1.1k-1 | — |
| Debian 13 | openssl | 1.1.1k-1 | — |
| Debian 12 | openssl | 1.1.1k-1 | — |
| Debian 10 | openssl | 1.1.1d-0+deb10u6 | DSA-4875-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | openssl | 1.1.1f-1ubuntu2.3 | USN-4891-1 |
| Ubuntu 20.04 LTS | postgresql-12 | 12.8-0ubuntu0.20.04.1 | USN-5038-1 |
| Ubuntu 18.04 LTS | openssl | 1.1.1-1ubuntu2.1~18.04.9 | USN-4891-1 |
| Ubuntu 18.04 LTS | postgresql-10 | 10.18-0ubuntu0.18.04.1 | USN-5038-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro FIPS 20.04 LTS | openssl | 1.1.1f-1ubuntu2.fips.2.8 | — |
| Ubuntu Pro FIPS 18.04 LTS | openssl | No fix yet | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | openssl | 1.1.1f-1ubuntu2.fips.7 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | openssl | 1.1.1-1ubuntu2.fips.2.1~18.04.9.1 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | openssl +3 | 1:1.1.1g-15.el8_3 | RHSA-2021:1024 |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Rhev Hypervisor 4 | redhat-virtualization-host +1 | 4.4.5-20210330.0.el8_3 | RHSA-2021:1189 |
| RHEL 8.2 EUS | openssl +3 | 1:1.1.1c-18.el8_2 | RHSA-2021:1063 |
| RHEL 8.1 EUS | openssl +3 | 1:1.1.1c-5.el8_1 | RHSA-2021:1131 |
| Red Hat JBoss Web Server 5 | jws5-tomcat-native | 1.2.25-4.redhat_4.el7jws | RHSA-2021:1195 |
| Red Hat JBoss Web Server 3 | tomcat-native | 1.2.23-24.redhat_24.ep7.el7 | RHSA-2021:1202 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-httpd +6 | 2.4.37-70.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_cluster-native | 1.3.14-20.Final_redhat_2.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_http2 | 1.15.7-14.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_jk +2 | 1.2.48-13.redhat_1.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_md | 1:2.0.8-33.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_security | 2.9.2-60.GA.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-mod_ssl +1 | 1:2.4.37-70.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-nghttp2 +1 | 1.39.2-37.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl +4 | 1:1.1.1g-6.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl-chil | 1.0.0-5.jbcs.el7 | RHSA-2021:1199 |
| Red Hat JBoss Core Services 1 | jbcs-httpd24-openssl-pkcs11 | 0.4.10-20.jbcs.el7 | RHSA-2021:1199 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | openssl | 1:1.1.1g-15.el8_3 | RLSA-2021:1024 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP3 | nodejs12 | 12.22.2-4.16.1 | SUSE-SU-2021:2327-1 |
| SLES 15 SP3 | openssl-1_1 | 1.1.1d-11.20.1 | SUSE-SU-2021:0955-2 |
| SLES 15 SP2 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SLES 15 SP2 | nodejs12 | 12.22.2-4.16.1 | SUSE-SU-2021:2327-1 |
| SLES 15 SP2 | openssl-1_1 | 1.1.1d-11.20.1 | SUSE-SU-2021:0955-1 |
| SLES 15 SP1 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SLES 15 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SLES 12 SP5 | openssl-1_1 | 1.1.1d-2.33.1 | SUSE-SU-2021:0954-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP4 | openssl-1_1 | 1.1.1d-2.33.1 | SUSE-SU-2021:0954-1 |
| SLES 12 | nodejs10 | 10.24.1-1.39.1 | SUSE-SU-2021:2323-1 |
| SLES 12 | nodejs12 | 12.22.2-1.32.1 | SUSE-SU-2021:2326-1 |
| SLES for SAP 15 SP1 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SLES for SAP 15 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SLES for SAP 12 SP5 | openssl-1_1 | 1.1.1d-2.33.1 | SUSE-SU-2021:0954-1 |
| SLES for SAP 12 SP4 | openssl-1_1 | 1.1.1d-2.33.1 | SUSE-SU-2021:0954-1 |
| SLE Micro 5.0 | openssl-1_1 | 1.1.1d-11.20.1 | SUSE-SU-2021:0955-1 |
| SLE HPC 15 SP1 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SLE HPC 15 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SUSE OpenStack Cloud Crowbar 9 | openssl-1_1 | 1.1.1d-2.33.1 | SUSE-SU-2021:0954-1 |
| SUSE OpenStack Cloud 9 | openssl-1_1 | 1.1.1d-2.33.1 | SUSE-SU-2021:0954-1 |
| SUSE Manager Server 4.0 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SUSE Manager Retail Branch Server 4.0 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SUSE Manager Proxy 4.0 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
| SUSE Enterprise Storage 6 | nodejs10 | 10.24.1-1.36.1 | SUSE-SU-2021:2353-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | matrix-synapse | 1.43.0-1.1 | openSUSE-SU-2024:11041-1 |
| openSUSE Tumbleweed | openssl-1_1 | 1.1.1l-1.2 | openSUSE-SU-2024:11127-1 |
| openSUSE Leap 15.3 | nodejs10 | 10.24.1-1.36.1 | openSUSE-SU-2021:2353-1 |
| openSUSE Leap 15.3 | nodejs12 | 12.22.2-4.16.1 | openSUSE-SU-2021:2327-1 |
| openSUSE Leap 15.2 | nodejs10 | 10.24.1-lp152.2.15.1 | openSUSE-SU-2021:1061-1 |
| openSUSE Leap 15.2 | nodejs12 | 12.22.2-lp152.3.15.1 | openSUSE-SU-2021:1059-1 |
| openSUSE Leap 15.2 | openssl-1_1 | 1.1.1d-lp152.7.15.1 | openSUSE-SU-2021:0476-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | openssl | 1.1.1k-r0 | — |
| Alpine v3.24 | synapse | 1.30.1-r0 | — |
| Alpine v3.23 | openssl | 1.1.1k-r0 | — |
| Alpine v3.23 | synapse | 1.30.1-r0 | — |
| Alpine v3.22 | openssl | 1.1.1k-r0 | — |
| Alpine v3.22 | synapse | 1.30.1-r0 | — |
| Alpine v3.21 | openssl | 1.1.1k-r0 | — |
| Alpine v3.21 | synapse | 1.30.1-r0 | — |
| Alpine v3.20 | openssl | 1.1.1k-r0 | — |
| Alpine v3.20 | synapse | 1.30.1-r0 | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | openssl | 1.1.1k-r0 | — |
| Alpine v3.19 | synapse | 1.30.1-r0 | — |
| Alpine v3.18 | openssl +1 | 1.1.1k-r0 | — |
| Alpine v3.18 | synapse | 1.30.1-r0 | — |
| Alpine v3.17 | openssl +1 | 1.1.1k-r0 | — |
| Alpine v3.17 | synapse | 1.30.1-r0 | — |
| Alpine v3.16 | openssl +1 | 1.1.1k-r0 | — |
| Alpine v3.16 | synapse | 1.30.1-r0 | — |
| Alpine v3.15 | openssl +1 | 1.1.1k-r0 | — |
| Alpine v3.15 | synapse | 1.30.1-r0 | — |
| Alpine v3.14 | openssl | 1.1.1k-r0 | — |
| Alpine v3.14 | synapse | 1.30.1-r0 | — |
| Alpine v3.13 | openssl | 1.1.1k-r0 | — |
| Alpine v3.13 | synapse | 1.30.1-r0 | — |
| Alpine v3.12 | openssl | 1.1.1k-r0 | — |
| Alpine v3.11 | openssl | 1.1.1k-r0 | — |
| Alpine v3.10 | openssl | 1.1.1k-r0 | — |
| Alpine v3.9 | openssl | 1.1.1k-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | edk2-ovmf +4 | 20200801stable-1.amzn2.0.5 | ALAS2-2024-2502 |
| Amazon Linux 2 | openssl11 +3 | 1:1.1.1g-12.amzn2.0.3 | ALAS2-2021-1622 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | openssl +3 | 1:1.1.1g-15.el8_3 | ELSA-2021-1024 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
-
riptl/cve-2021-3449 ★ 223 · Mar 26, 2021
CVE-2021-3449 OpenSSL denial-of-service exploit 👨🏻💻
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| crates.io | openssl-src | < 111.15.0 | 111.15.0 | GHSA-83mx-573x-5rw9 |
| crates.io | openssl-src | >= 0.0.0-0, < 111.15.0 | 111.15.0 | RUSTSEC-2021-0055 |
Advisories 38
- RHSA-2021:1202 Red Hat Security Advisory: Red Hat JBoss Web Server 3.1 Service Pack 12 security update Red Hat Security Advisories (RHSA) · Oct 9, 2026
- RHSA-2021:1199 Red Hat Security Advisory: Red Hat JBoss Core Services Apache HTTP Server 2.4.37 SP7 security update Red Hat Security Advisories (RHSA) · Oct 9, 2026
- RHSA-2021:1189 Red Hat Security Advisory: Red Hat Virtualization security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Oct 9, 2026
- RHSA-2021:1195 Red Hat Security Advisory: Red Hat JBoss Web Server 5.4.2 Security Update Red Hat Security Advisories (RHSA) · Oct 9, 2026
- RHSA-2021:1024 Red Hat Security Advisory: openssl security update Red Hat Security Advisories (RHSA) · Oct 9, 2026
- RHSA-2021:1063 Red Hat Security Advisory: openssl security update Red Hat Security Advisories (RHSA) · Sep 21, 2026
- RHSA-2021:1131 Red Hat Security Advisory: openssl security update Red Hat Security Advisories (RHSA) · Sep 21, 2026
- WID-SEC-2024-0794 Dell ECS: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 11, 2026
- WID-SEC-2025-0227 IBM QRadar SIEM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 11, 2026
- USN-5038-1 postgresql-10, postgresql-12, postgresql-13 vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- USN-4891-1 openssl vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-4875-1 openssl - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2021:1024 Important: openssl security update Rocky Linux Security Advisories · Feb 5, 2026
- SUSE-SU-2021:2327-1 Security update for nodejs12 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:0955-1 Security update for openssl-1_1 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:2353-1 Security update for nodejs10 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2323-1 Security update for nodejs10 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2353-1 Security update for nodejs10 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:0954-1 Security update for openssl-1_1 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:2327-1 Security update for nodejs12 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1059-1 Security update for nodejs12 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:0476-1 Security update for openssl-1_1 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1061-1 Security update for nodejs10 SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11041-1 matrix-synapse-1.43.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:0955-2 Security update for openssl-1_1 SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:2326-1 Security update for nodejs12 SUSE / openSUSE Security Updates · Feb 4, 2026
- ALAS2-2024-2502 Important: edk2 security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 23, 2025
- VDE-2021-025 PHOENIX CONTACT: Security Advisory for PLCNext, ILC 2050 BI, FL MGUARD DM UNLIMITED, TC ROUTER und CLOUD CLIENT products CERT@VDE · May 14, 2025
- openSUSE-SU-2024:11127-1 libopenssl-1_1-devel-1.1.1l-1.2 on GA media SUSE / openSUSE Security Updates · May 7, 2025
- ICSA-22-069-09 Siemens SINEC INS CISA ICS & IT advisories · May 6, 2025
- WID-SEC-2022-0671 OpenSSL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 25, 2024
- SSA-772220 SSA-772220: OpenSSL Vulnerabilities in Industrial Products Siemens ProductCERT · Jan 9, 2024
- ICSA-22-104-05 Siemens OpenSSL Vulnerabilities in Industrial Products CISA ICS & IT advisories · Jan 9, 2024
- WID-SEC-2023-0065 Oracle MySQL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 27, 2023
- SSA-389290 SSA-389290: Third-Party Component Vulnerabilities in SINEC INS Siemens ProductCERT · Mar 8, 2022
- ICSA-21-336-06 Hitachi Energy APM Edge CISA ICS & IT advisories · Dec 2, 2021
- ELSA-2021-1024 Important: openssl security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Mar 29, 2021
- ALAS2-2021-1622 Important: openssl11 security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Mar 25, 2021
References
- https://www.openssl.org/news/secadv/20210325.txt
- https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=fb9fa6b51defd48157eeb207f52181f735d96148
- 20210325 Multiple Vulnerabilities in OpenSSL Affecting Cisco Products: March 2021 vendor-advisory
- DSA-4875 vendor-advisory
- [oss-security] 20210327 OpenSSL 1.1.1 CVE-2021-3450 CA certificate check bypass with X509_V_FLAG_X509_STRICT, CVE-2021-3449 NULL pointer deref in signature_algorithms processing mailing-list
- [oss-security] 20210327 Re: OpenSSL 1.1.1 CVE-2021-3450 CA certificate check bypass with X509_V_FLAG_X509_STRICT, CVE-2021-3449 NULL pointer deref in signature_algorithms processing mailing-list
- [oss-security] 20210328 Re: OpenSSL 1.1.1 CVE-2021-3450 CA certificate check bypass with X509_V_FLAG_X509_STRICT, CVE-2021-3449 NULL pointer deref in signature_algorithms processing mailing-list
- [oss-security] 20210328 Re: OpenSSL 1.1.1 CVE-2021-3450 CA certificate check bypass with X509_V_FLAG_X509_STRICT, CVE-2021-3449 NULL pointer deref in signature_algorithms processing mailing-list
- GLSA-202103-03 vendor-advisory
- FEDORA-2021-cbf14ab8f9 vendor-advisory
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://www.tenable.com/security/tns-2021-10
- https://www.tenable.com/security/tns-2021-09
- https://security.netapp.com/advisory/ntap-20210513-0002/
- https://security.netapp.com/advisory/ntap-20210326-0006/
- https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.asc
- https://www.tenable.com/security/tns-2021-06
- https://www.tenable.com/security/tns-2021-05
- https://kc.mcafee.com/corporate/index?page=content&id=SB10356
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-772220.pdf
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013
- [debian-lts-announce] 20210831 [SECURITY] [DLA 2751-1] postgresql-9.6 security update mailing-list
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://security.netapp.com/advisory/ntap-20240621-0006/