DEBIAN-CVE-2026-42770
Issue summary: When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the peer key is not properly checked for the subgroup membership. Impact summary: A malicious peer which presents an X9.42 key carrying the victim's p and g parameters, a forged q = r (a small prime factor of the cofactor (p−1)/q_local), and a public value Y of order r can recover the victim's private key after a small number of key exchange attempts. When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the subgroup membership check Y^q ≡ 1 (mod p) is performed using the peer's own q parameter, not the local key's q. The peer's domain parameters are then matched against the domain parameters of the private key, but the value of q is not compared. A malicious peer who presents an X9.42 key carrying the victim's p, g, a forged q = r (a small prime factor of the cofactor), and a public value Y of order r passes all checks. The shared secret then takes only r distinct values, leaking priv mod r. Repeating for each small-prime factor of the cofactor and combining via CRT recovers the full private key (Lim–Lee / small-subgroup-confinement attack). The realistic attack surface is narrow: principally CMP deployments with long-lived RA/CA DHX keys and bespoke enterprise or government applications using X9.42 DHX static keys with interactive protocols and therefore this issue was assigned Low severity. The FIPS modules in 4.0, 3.6, 3.5, 3.4, 3.1.2 and 3.0 are affected by this issue.
DEBIAN-CVE-2026-42770
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-2026-42770
openssl
Source reference: /affected/0/package/name
- Affected versions
- 3.0.10-1
Source reference:
/affected/0/versions3.0.10-1~deb12u1Source reference:
/affected/0/versions3.0.11-1Source reference:
/affected/0/versions3.0.11-1~deb12u1Source reference:
/affected/0/versions3.0.11-1~deb12u2Source reference:
/affected/0/versions3.0.12-1Source reference:
/affected/0/versions3.0.12-2Source reference:
/affected/0/versions3.0.13-1~deb12u1Source reference:
/affected/0/versions3.0.13-1~deb12u2Source reference:
/affected/0/versions3.0.14-1~deb12u1Source reference:
/affected/0/versions3.0.14-1~deb12u2Source reference:
/affected/0/versions3.0.15-1~deb12u1Source reference:
/affected/0/versions3.0.16-1~deb12u1Source reference:
/affected/0/versions3.0.17-1~deb12u1Source reference:
/affected/0/versions3.0.17-1~deb12u2Source reference:
/affected/0/versions3.0.17-1~deb12u3Source reference:
/affected/0/versions3.0.18-1~deb12u1Source reference:
/affected/0/versions3.0.18-1~deb12u2Source reference:
/affected/0/versions3.0.19-1~deb12u1Source reference:
/affected/0/versions3.0.19-1~deb12u2Source reference:
/affected/0/versions3.0.20-1~deb12u1Source reference:
/affected/0/versions3.0.9-1Source reference:
/affected/0/versions - Fixed versions
- 3.0.20-1~deb12u2
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/versions3.5.1-1+deb13u1Source 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/versions - Fixed versions
- 3.5.6-1~deb13u2
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
openssl
Source reference: /affected/2/package/name
- Affected versions
- 3.5.1-1
Source reference:
/affected/2/versions3.5.2-1Source reference:
/affected/2/versions3.5.3-1Source reference:
/affected/2/versions3.5.4-1Source reference:
/affected/2/versions3.5.4-1~deb13u1Source reference:
/affected/2/versions3.5.4-1~deb13u2Source reference:
/affected/2/versions3.5.5-1Source reference:
/affected/2/versions3.5.5-1~deb13u1Source reference:
/affected/2/versions3.5.5-1~deb13u2Source reference:
/affected/2/versions3.5.6-1~deb13u1Source reference:
/affected/2/versions3.5.6-1~deb13u2Source reference:
/affected/2/versions3.5.7-1~deb13u1Source reference:
/affected/2/versions3.5.7-1~deb13u2Source reference:
/affected/2/versions3.5.7-1~deb13u3Source reference:
/affected/2/versions3.6.0-1Source reference:
/affected/2/versions3.6.0-2Source reference:
/affected/2/versions3.6.0~~alpha1-1Source reference:
/affected/2/versions3.6.0~~beta1-1Source reference:
/affected/2/versions3.6.1-1Source reference:
/affected/2/versions3.6.1-2Source reference:
/affected/2/versions3.6.1-3Source reference:
/affected/2/versions3.6.2-1Source reference:
/affected/2/versions - Fixed versions
- 3.6.3-1
Source reference:
/affected/2/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": "3.0.20-1~deb12u2"
}
]
}
],
"package": {
"name": "openssl",
"purl": "pkg:deb/debian/openssl?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"3.0.10-1",
"3.0.10-1~deb12u1",
"3.0.11-1",
"3.0.11-1~deb12u1",
"3.0.11-1~deb12u2",
"3.0.12-1",
"3.0.12-2",
"3.0.13-1~deb12u1",
"3.0.13-1~deb12u2",
"3.0.14-1~deb12u1",
"3.0.14-1~deb12u2",
"3.0.15-1~deb12u1",
"3.0.16-1~deb12u1",
"3.0.17-1~deb12u1",
"3.0.17-1~deb12u2",
"3.0.17-1~deb12u3",
"3.0.18-1~deb12u1",
"3.0.18-1~deb12u2",
"3.0.19-1~deb12u1",
"3.0.19-1~deb12u2",
"3.0.20-1~deb12u1",
"3.0.9-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42770.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.5.6-1~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",
"3.5.5-1~deb13u1",
"3.5.5-1~deb13u2",
"3.5.6-1~deb13u1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42770.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6.3-1"
}
]
}
],
"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",
"3.6.2-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42770.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #56972 · Revision 1
- Added to Heist Feed
- Publisher date