# CVE-2026-2673: OpenSSL TLS 1.3 server may choose unexpected key agreement group

CVE-2026-2673 is fixed in 14 products on 1 platform, first by RHSA-2026:19066, released March 13, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-2673
- Priority: Routine
- CVSS: 6.5 (Moderate)
- EPSS: 0.0045
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 13, 2026
- Weakness: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-2673

## Description

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols, as well as a full-strength general-purpose cryptography library.  Security Fix(es):  * openssl: OpenSSL: Denial of Service due to NULL pointer dereference in CMS EnvelopedData processing (CVE-2026-28390)  For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libssl3t64 Ubuntu 25.10 (questing) | 3.5.3-1ubuntu3.3 | [libssl3t64 3.5.3-1ubuntu3.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libssl3t64-3.5.3-1ubuntu3.3.md) | Apr 15, 2026 |
| Linux | libssl3t64 Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3 | [libssl3t64 3.5.5-1ubuntu3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libssl3t64-3.5.5-1ubuntu3.md) | Apr 6, 2026 |
| Linux | openssl Debian 13.5 (trixie) | 3.5.5-1~deb13u2 | [DEBIAN-CVE-2026-2673](https://patchblox.com/security/data/fix/linux/debian-cve-2026-2673.md) | Mar 13, 2026 |
| Linux | openssl Debian 14 | 3.6.2-1 | [DEBIAN-CVE-2026-2673](https://patchblox.com/security/data/fix/linux/debian-cve-2026-2673.md) | Mar 13, 2026 |
| Linux | openssl RHEL 10 | 3.5.5-2.el10_2 | [RHSA-2026:19066](https://patchblox.com/security/data/fix/linux/rhsa-2026-19066.md) | Mar 13, 2026 |
| Linux | openssl RHEL 9 | 1:3.5.5-3.el9_8 | [RHSA-2026:22312](https://patchblox.com/security/data/fix/linux/rhsa-2026-22312.md) | Jun 24, 2026 |
| Linux | openssl Ubuntu 25.10 (questing) | 3.5.3-1ubuntu3.3 | [openssl 3.5.3-1ubuntu3.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-openssl-3.5.3-1ubuntu3.3.md) | Apr 15, 2026 |
| Linux | openssl Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3 | [openssl 3.5.5-1ubuntu3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-openssl-3.5.5-1ubuntu3.md) | Apr 6, 2026 |
| Linux | openssl almalinux 10 | 1:3.5.5-2.el10_2.alma.1 | [ALSA-2026:19066](https://patchblox.com/security/data/fix/linux/alsa-2026-19066.md) | May 19, 2026 |
| Linux | openssl almalinux 9 | 1:3.5.5-3.el9_8 | [ALSA-2026:22312](https://patchblox.com/security/data/fix/linux/alsa-2026-22312.md) | Jun 1, 2026 |
| Linux | openssl amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-3 opensuse-leap 16.0 | 3.5.0-160000.8.1 | [OPENSUSE-SU-2026:21005-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21005-1.md) | Jun 22, 2026 |
| Linux | openssl-3 sles 16.0 | 3.5.0-160000.8.1 | [SUSE-SU-2026:22315-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22315-1.md) | Jun 22, 2026 |
| Linux | openssl-debuginfo amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-debugsource amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-devel RHEL 9 | 1:3.5.5-3.el9_8 | [RHSA-2026:22312](https://patchblox.com/security/data/fix/linux/rhsa-2026-22312.md) | Jun 24, 2026 |
| Linux | openssl-devel almalinux 10 | 1:3.5.5-2.el10_2.alma.1 | [ALSA-2026:19066](https://patchblox.com/security/data/fix/linux/alsa-2026-19066.md) | May 19, 2026 |
| Linux | openssl-devel almalinux 9 | 1:3.5.5-3.el9_8 | [ALSA-2026:22312](https://patchblox.com/security/data/fix/linux/alsa-2026-22312.md) | Jun 1, 2026 |
| Linux | openssl-devel amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-fips-provider-latest amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-fips-provider-latest-debuginfo amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-libs RHEL 9 | 1:3.5.5-3.el9_8 | [RHSA-2026:22312](https://patchblox.com/security/data/fix/linux/rhsa-2026-22312.md) | Jun 24, 2026 |
| Linux | openssl-libs almalinux 10 | 1:3.5.5-2.el10_2.alma.1 | [ALSA-2026:19066](https://patchblox.com/security/data/fix/linux/alsa-2026-19066.md) | May 19, 2026 |
| Linux | openssl-libs almalinux 9 | 1:3.5.5-3.el9_8 | [ALSA-2026:22312](https://patchblox.com/security/data/fix/linux/alsa-2026-22312.md) | Jun 1, 2026 |
| Linux | openssl-libs amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-libs-debuginfo amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-perl RHEL 9 | 1:3.5.5-3.el9_8 | [RHSA-2026:22312](https://patchblox.com/security/data/fix/linux/rhsa-2026-22312.md) | Jun 24, 2026 |
| Linux | openssl-perl almalinux 10 | 1:3.5.5-2.el10_2.alma.1 | [ALSA-2026:19066](https://patchblox.com/security/data/fix/linux/alsa-2026-19066.md) | May 19, 2026 |
| Linux | openssl-perl almalinux 9 | 1:3.5.5-3.el9_8 | [ALSA-2026:22312](https://patchblox.com/security/data/fix/linux/alsa-2026-22312.md) | Jun 1, 2026 |
| Linux | openssl-perl amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-provider-legacy Ubuntu 25.10 (questing) | 3.5.3-1ubuntu3.3 | [openssl-provider-legacy 3.5.3-1ubuntu3.3](https://patchblox.com/security/data/fix/linux/ubuntu-questing-openssl-provider-legacy-3.5.3-1ubuntu3.3.md) | Apr 15, 2026 |
| Linux | openssl-provider-legacy Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3 | [openssl-provider-legacy 3.5.5-1ubuntu3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-openssl-provider-legacy-3.5.5-1ubuntu3.md) | Apr 6, 2026 |
| Linux | openssl-snapsafe-libs amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |
| Linux | openssl-snapsafe-libs-debuginfo amzn 2023 | 1:3.5.5-1.amzn2023.0.3 | [ALAS2023-2026-1522](https://patchblox.com/security/data/fix/linux/alas2023-2026-1522.md) | Mar 30, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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