CVE-2026-55653Disclosure(openbsd / enterprise_linux)

MEDIUMCVSS 6.5 · MEDIUM

Exploitation ongoing with high activity in latest observed window (4 mentions)

Immediate actions

Prioritize remediation for openbsd enterprise_linux systems immediately
Assume compromise if assets are exposed
Track advisory updates for patch or workaround availability

Recommended action window: Immediate (within 24h)

NVD description

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).

openbsd CVEs Back to dashboard

4.5/ 10 priority

Sources & remediation

Exploit / PoC references

https://bugzilla.redhat.com/show_bug.cgi?id=2462351

Vendor / third-party advisories

https://access.redhat.com/security/cve/CVE-2026-55653

Other references

Weakness type (CWE)

CWE-415

Priority

MEDIUM

Exploitation

ACTIVE

PoC

YES

Patch

NONE

Momentum

NONE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

enterprise_linux
hardened_images
openshift_container_platform
openssh

Threat summary

Active exploitation appears in 1 classified signals
4 mentions across 1 observed day

What's happening

Active exploitation reported across 1 signal
Technical details provided in 2 signals
Disclosure: 3 classified signals
4 total mentions across 1 day

Affected systems

Vendors

openbsd redhat

Products

enterprise_linuxhardened_imagesopenshift_container_platformopenssh

7 versions affected across 4 products

Deep dive

Activity timeline4 mentions / 1d

Signal classification2 categories

Disclosure

375.0%

Active Exploitation

125.0%

Referenced assets4 URLs

By indicator

Full discourse4 posts

VulDB 🛡@vuldb91d
Active Exploitation
Our CTI team identified a lot of activities targeting OpenSSH (CVE-2026-55653) https://vuldb.com/vuln/372805/cti
Post summary
The CTI notice indicates multiple targeting activities against OpenSSH (CVE-2026-55653), pointing to potential active exploitation, but lacks detailed technical or mitigation information.
00000114
2.2K followersView on X
Infoflowcloud@infoflowcloud91d
Disclosure
🚨*CVE* CVE-2026-55653 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 dur… https://www.cve.org/CVERecord?id=CVE-2026-55653 ----- Traducción: Se encontró una fa… http://infoflow.cloud`
Post summary
A new double‑free vulnerability in OpenSSH’s DH‑GEX client path (CVE‑2026‑55653) has been disclosed, providing technical details but no evidence of active exploitation, PoC, or mitigation steps.
0000045
88 followersView on X
CVE@CVEnew91d
Disclosure
CVE-2026-55653 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 dur… https://www.cve.org/CVERecord?id=CVE-2026-55653
Post summary
The text announces that OpenSSH has a double‑free vulnerability (CVE‑2026‑55653) affecting the Diffie‑Hellman Group Exchange client path, with no proof of exploitation, patches, or active attacks reported.
00000814
57.7K followersView on X
VulDB 🛡@vuldb91d
Disclosure
We have just added an important vulnerability affecting OpenSSH (CVE-2026-55653) https://vuldb.com/vuln/372805
Post summary
The post announces the addition of a new vulnerability affecting OpenSSH (CVE-2026-55653) and links to a vulnerability database entry for more information.
00000118
2.2K followersView on X

CPE platform detail8 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

8 of 8 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	openbsd	openssh	-	-	-
OS	redhat	enterprise_linux	10.0	-	-
OS	redhat	enterprise_linux	6.0	-	-
OS	redhat	enterprise_linux	7.0	-	-
OS	redhat	enterprise_linux	8.0	-	-
OS	redhat	enterprise_linux	9.0	-	-
App	redhat	hardened_images	-	-	-
App	redhat	openshift_container_platform	4.0	-	-

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What researchers are saying

CVE-2026-55653

VulDB 🛡@vuldbActive Exploitation

The CTI notice indicates multiple targeting activities against OpenSSH (CVE-2026-55653), pointing to potential active exploitation, but lacks detailed technical or mitigation information.

Infoflowcloud@infoflowcloudDisclosure

A new double‑free vulnerability in OpenSSH’s DH‑GEX client path (CVE‑2026‑55653) has been disclosed, providing technical details but no evidence of active exploitation, PoC, or mitigation steps.

CVE@CVEnewDisclosure

The text announces that OpenSSH has a double‑free vulnerability (CVE‑2026‑55653) affecting the Diffie‑Hellman Group Exchange client path, with no proof of exploitation, patches, or active attacks reported.

VulDB 🛡@vuldbDisclosure

The post announces the addition of a new vulnerability affecting OpenSSH (CVE-2026-55653) and links to a vulnerability database entry for more information.