OpenSSL TLS 1.3 Server Vulnerability in Key Exchange Negotiation
CVE-2026-2673

7.5HIGH

Key Information:

Vendor

OpenSSL
Status
OpenSSL
Vendor
CVE Published:
13 March 2026

What is CVE-2026-2673?

An defect in the OpenSSL TLS 1.3 server's key exchange negotiation process may lead to the selection of less preferred key exchange groups, impacting secure communications. When configured with the 'DEFAULT' keyword, the server may mishandle the group list, resulting in an inability to negotiate mutually supported post-quantum key agreement groups. This issue arises when clients defer their use of certain keyshares, preventing the correct selection of the most secure group. Users of OpenSSL 3.5 and 3.6 are advised to upgrade to the respective patched versions to mitigate this risk and enhance security.

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Affected Version(s)

OpenSSL 3.6.0 < 3.6.2

OpenSSL 3.5.0 < 3.5.6

References

https://openssl-library.org/news/secadv/20260313.txt
vendor-advisory
https://github.com/openssl/openssl/commit/2157c9d81f7b0bd...
patch
https://github.com/openssl/openssl/commit/85977e013f32ceb...
patch

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Viktor Dukhovni
Viktor Dukhovni
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