DEBIAN-CVE-2026-2673
Issue summary: An OpenSSL TLS 1.3 server may fail to negotiate the expected preferred key exchange group when its key exchange group configuration includes the default by using the 'DEFAULT' keyword. Impact summary: A less preferred key exchange may be used even when a more preferred group is supported by both client and server, if the group was not included among the client's initial predicated keyshares. This will sometimes be the case with the new hybrid post-quantum groups, if the client chooses to defer their use until specifically requested by the server. If an OpenSSL TLS 1.3 server's configuration uses the 'DEFAULT' keyword to interpolate the built-in default group list into its own configuration, perhaps adding or removing specific elements, then an implementation defect causes the 'DEFAULT' list to lose its 'tuple' structure, and all server-supported groups were treated as a single sufficiently secure 'tuple', with the server not sending a Hello Retry Request (HRR) even when a group in a more preferred tuple was mutually supported. As a result, the client and server might fail to negotiate a mutually supported post-quantum key agreement group, such as 'X25519MLKEM768', if the client's configuration results in only 'classical' groups (such as 'X25519' being the only ones in the client's initial keyshare prediction). OpenSSL 3.5 and later support a new syntax for selecting the most preferred TLS 1.3 key agreement group on TLS servers. The old syntax had a single 'flat
DEBIAN-CVE-2026-2673
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:DEBIAN-CVE-2026-2673
openssl
Source reference: /affected/0/package/name
- Affected versions
- 3.5.1-1
Source reference:
/affected/0/versions3.5.1-1+deb13u1Source reference:
/affected/0/versions3.5.2-1Source reference:
/affected/0/versions3.5.3-1Source reference:
/affected/0/versions3.5.4-1Source reference:
/affected/0/versions3.5.4-1~deb13u1Source reference:
/affected/0/versions3.5.4-1~deb13u2Source reference:
/affected/0/versions3.5.5-1~deb13u1Source reference:
/affected/0/versions - Fixed versions
- 3.5.5-1~deb13u2
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
openssl
Source reference: /affected/1/package/name
- Affected versions
- 3.5.1-1
Source reference:
/affected/1/versions3.5.2-1Source reference:
/affected/1/versions3.5.3-1Source reference:
/affected/1/versions3.5.4-1Source reference:
/affected/1/versions3.5.4-1~deb13u1Source reference:
/affected/1/versions3.5.4-1~deb13u2Source reference:
/affected/1/versions3.5.5-1Source reference:
/affected/1/versions3.5.5-1~deb13u1Source reference:
/affected/1/versions3.5.5-1~deb13u2Source reference:
/affected/1/versions3.5.6-1~deb13u1Source reference:
/affected/1/versions3.5.6-1~deb13u2Source reference:
/affected/1/versions3.5.7-1~deb13u1Source reference:
/affected/1/versions3.5.7-1~deb13u2Source reference:
/affected/1/versions3.5.7-1~deb13u3Source reference:
/affected/1/versions3.6.0-1Source reference:
/affected/1/versions3.6.0-2Source reference:
/affected/1/versions3.6.0~~alpha1-1Source reference:
/affected/1/versions3.6.0~~beta1-1Source reference:
/affected/1/versions3.6.1-1Source reference:
/affected/1/versions3.6.1-2Source reference:
/affected/1/versions3.6.1-3Source reference:
/affected/1/versions - Fixed versions
- 3.6.2-1
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.5.5-1~deb13u2"
}
]
}
],
"package": {
"name": "openssl",
"purl": "pkg:deb/debian/openssl?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"3.5.1-1",
"3.5.1-1+deb13u1",
"3.5.2-1",
"3.5.3-1",
"3.5.4-1",
"3.5.4-1~deb13u1",
"3.5.4-1~deb13u2",
"3.5.5-1~deb13u1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-2673.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6.2-1"
}
]
}
],
"package": {
"name": "openssl",
"purl": "pkg:deb/debian/openssl?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"3.5.1-1",
"3.5.2-1",
"3.5.3-1",
"3.5.4-1",
"3.5.4-1~deb13u1",
"3.5.4-1~deb13u2",
"3.5.5-1",
"3.5.5-1~deb13u1",
"3.5.5-1~deb13u2",
"3.5.6-1~deb13u1",
"3.5.6-1~deb13u2",
"3.5.7-1~deb13u1",
"3.5.7-1~deb13u2",
"3.5.7-1~deb13u3",
"3.6.0-1",
"3.6.0-2",
"3.6.0~~alpha1-1",
"3.6.0~~beta1-1",
"3.6.1-1",
"3.6.1-2",
"3.6.1-3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-2673.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #56272 · Revision 1
- Added to Heist Feed
- Publisher date