DEBIAN-CVE-2026-50721
Libreswan, via the function RSA_authenticate_hash_signature_raw_rsa(), did not correctly verify the length of the authentication hash when the SIG payload of an IKEv1 packet was encoded using PKCS #1 RSA Encryption as per RFC 2313. A remote attacker can use a variation on the Bleichenbacher attack to forge the SIG payload when small public exponents are being used (e.g., e=3), which could lead to impersonation. Additionally, a remote attacker, by encoding a shorter than expected hash in the SIG payload, could trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications of remote IKE peers are not affected.
DEBIAN-CVE-2026-50721
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-2026-50721
libreswan
Source reference: /affected/0/package/name
- Affected versions
- 4.10-2
Source reference:
/affected/0/versions4.10-2+deb12u1Source reference:
/affected/0/versions4.11-1Source reference:
/affected/0/versions4.12-1Source reference:
/affected/0/versions4.12-2Source reference:
/affected/0/versions4.12-3Source reference:
/affected/0/versions4.14-1Source reference:
/affected/0/versions4.14-1.1Source reference:
/affected/0/versions4.15-1Source reference:
/affected/0/versions5.0~rc2-1Source reference:
/affected/0/versions5.0~rc2-2Source reference:
/affected/0/versions5.2-1Source reference:
/affected/0/versions5.2-2Source reference:
/affected/0/versions5.2-2.1Source reference:
/affected/0/versions5.2-2.2Source reference:
/affected/0/versions5.2-2.3Source reference:
/affected/0/versions5.2-2.4Source reference:
/affected/0/versions5.2-2.5Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
libreswan
Source reference: /affected/1/package/name
- Affected versions
- 5.2-2.2
Source reference:
/affected/1/versions5.2-2.3Source reference:
/affected/1/versions5.2-2.4Source reference:
/affected/1/versions5.2-2.5Source reference:
/affected/1/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
libreswan
Source reference: /affected/2/package/name
- Affected versions
- 5.2-2.2
Source reference:
/affected/2/versions5.2-2.3Source reference:
/affected/2/versions5.2-2.4Source reference:
/affected/2/versions - Fixed versions
- 5.2-2.5
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"
}
]
}
],
"package": {
"name": "libreswan",
"purl": "pkg:deb/debian/libreswan?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"4.10-2",
"4.10-2+deb12u1",
"4.11-1",
"4.12-1",
"4.12-2",
"4.12-3",
"4.14-1",
"4.14-1.1",
"4.15-1",
"5.0~rc2-1",
"5.0~rc2-2",
"5.2-1",
"5.2-2",
"5.2-2.1",
"5.2-2.2",
"5.2-2.3",
"5.2-2.4",
"5.2-2.5"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-50721.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libreswan",
"purl": "pkg:deb/debian/libreswan?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"5.2-2.2",
"5.2-2.3",
"5.2-2.4",
"5.2-2.5"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-50721.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "5.2-2.5"
}
]
}
],
"package": {
"name": "libreswan",
"purl": "pkg:deb/debian/libreswan?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"5.2-2.2",
"5.2-2.3",
"5.2-2.4"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-50721.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #57250 · Revision 1
- Added to Heist Feed
- Publisher date