CVE catalog

CVE-2026-55653

Severity: Medium · CVSS 6.5CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Published: Jun 22, 2026, 10:00:00 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.43% · Oct 25, 2026

A flaw was found in OpenSSH. A malicious SSH server can exploit a double free vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This occurs during FIPS (Federal Information Processing Standards) mode known-group validation when the client processes attacker-controlled DH-GEX group parameters. Successful exploitation leads to client-side process termination, resulting in a Denial of Service (DoS).

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	openssh	sid	`1:10.6p1-1`	not affected
Debian	openssh	forky	`1:10.6p1-1`	not affected
Debian	openssh	trixie	`1:10.0p1-7+deb13u4`	not affected
Debian	openssh	trixie-security	`1:10.0p1-7+deb13u2`	not affected
Debian	openssh	bookworm	`1:9.2p1-2+deb12u10`	not affected
Debian	openssh	bookworm-security	`1:9.2p1-2+deb12u9`	not affected
Cpe	openssh	Not reported	Not reported	unknown
Cpe	hardened_images	Not reported	Not reported	unknown
Cpe	openshift_container_platform	Not reported	Not reported	unknown
Cpe	enterprise_linux	Not reported	Not reported	unknown
Cpe	openssh	Not reported	Not reported	not affected
Cpe	openssh	Not reported	Not reported	unknown
Cpe	hardened_images	Not reported	Not reported	unknown
Cpe	openshift_container_platform	Not reported	Not reported	unknown
Cpe	enterprise_linux	Not reported	Not reported	unknown
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.7+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.12+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.13+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.14+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.15+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.16+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.16+Fips2`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.18+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.19+Fips1`	vulnerable
Ubuntu	openssh	pro	`1:9.6p1-3ubuntu13.20+Fips1`	vulnerable
Ubuntu	openssh-ssh1	18.04	`1:7.5p1-8`	vulnerable
Ubuntu	openssh-ssh1	18.04	`1:7.5p1-9`	vulnerable
Ubuntu	openssh-ssh1	18.04	`1:7.5p1-9build1`	vulnerable
Ubuntu	openssh-ssh1	18.04	`1:7.5p1-10`	vulnerable
Ubuntu	openssh-ssh1	20.04	`1:7.5p1-11build1`	vulnerable
Ubuntu	openssh-ssh1	22.04	`1:7.5p1-12`	vulnerable
Ubuntu	openssh-ssh1	22.04	`1:7.5p1-12build1`	vulnerable
Ubuntu	openssh-ssh1	22.04	`1:7.5p1-13`	vulnerable
Ubuntu	openssh-ssh1	24.04	`1:7.5p1-14`	vulnerable
Ubuntu	openssh-ssh1	24.04	`1:7.5p1-15`	vulnerable
Ubuntu	openssh-ssh1	24.04	`1:7.5p1-15build1`	vulnerable
Ubuntu	openssh-ssh1	24.04	`1:7.5p1-16`	vulnerable
Ubuntu	openssh-ssh1	25.10	`1:7.5p1-17`	vulnerable
Ubuntu	openssh-ssh1	26.10	`1:7.5p1-18`	vulnerable
Ubuntu	openssh-ssh1	26.10	`1:7.5p1-18ubuntu1`	vulnerable
Ubuntu	openssh-ssh1	26.10	`1:7.5p1-18ubuntu2`	vulnerable
Ubuntu	openssh-ssh1	26.04	`1:7.5p1-17`	vulnerable
Ubuntu	openssh-ssh1	26.04	`1:7.5p1-18`	vulnerable

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	openssh	source	sid	`Not affected`	unimportant	Not reported	Not reported
Debian	openssh	source	forky	`Not affected`	unimportant	Not reported	Not reported
Debian	openssh	source	trixie	`Not affected`	unimportant	Not reported	Not reported
Debian	openssh	source	bookworm	`Not affected`	unimportant	Not reported	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[openssh-client]Not affected
Source package: [openssh]
Details (8)
- 1:9.2p1-2+deb12u10 · amd64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u10 · arm64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · amd64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · arm64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · amd64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · arm64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · amd64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · arm64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
[openssh-client-gssapi]Not affected
Source package: [openssh]
Details (2)
- 1:10.0p1-7~bpo12+1 · all · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · all · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
[openssh-server]Not affected
Source package: [openssh]
Details (8)
- 1:9.2p1-2+deb12u10 · amd64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u10 · arm64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · amd64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · arm64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · amd64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · arm64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · amd64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · arm64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
[openssh-server-gssapi]Not affected
Source package: [openssh]
Details (2)
- 1:10.0p1-7~bpo12+1 · all · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · all · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
[openssh-sftp-server]Not affected
Source package: [openssh]
Details (8)
- 1:9.2p1-2+deb12u10 · amd64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u10 · arm64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · amd64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · arm64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · amd64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · arm64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · amd64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · arm64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
[openssh-tests]Not affected
Source package: [openssh]
Details (8)
- 1:9.2p1-2+deb12u10 · amd64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u10 · arm64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · amd64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · arm64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · amd64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · arm64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · amd64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · arm64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
[ssh]Not affected
Source package: [openssh]
Details (8)
- 1:9.2p1-2+deb12u10 · all · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u10 · all · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · all · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · all · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · all · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · all · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · all · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · all · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
[ssh-askpass-gnome]Not affected
Source package: [openssh]
Details (8)
- 1:9.2p1-2+deb12u10 · amd64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u10 · arm64 · bookworm
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · amd64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:10.0p1-7~bpo12+1 · arm64 · bookworm-backports
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · amd64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u9 · arm64 · bookworm-security
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · amd64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm
- 1:9.2p1-2+deb12u7 · arm64 · bookworm-updates
  Not affected
  nvd · openssh · debian · bookworm

Observed: Oct 27, 2026, 7:14:04 AM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]