CVE-2026-55653: Double Free in Red Hat Red Hat Enterprise Linux 10
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).
AI Analysis
Technical Summary
CVE-2026-55653 is a double free vulnerability in the OpenSSH client on Red Hat Enterprise Linux 10. It occurs during the Diffie-Hellman Group Exchange (DH-GEX) client path when operating in FIPS mode, specifically during known-group validation of DH-GEX parameters supplied by a malicious SSH server. Successful exploitation causes client-side process termination, leading to denial of service. Red Hat has published security advisories and released updated OpenSSH packages (version 10.3p1-6.hum1) that fix this vulnerability.
Potential Impact
The vulnerability allows a malicious SSH server to cause the OpenSSH client to crash by triggering a double free condition during DH-GEX group parameter validation in FIPS mode. This results in denial of service on the client side. There is no indication of confidentiality or integrity impact, and no known exploits in the wild have been reported.
Mitigation Recommendations
Red Hat has released updated OpenSSH packages (openssh-10.3p1-6.hum1) that fix this vulnerability. Users of Red Hat Enterprise Linux 10 should apply these official updates promptly to remediate the issue. Patch status is confirmed by Red Hat advisories. No additional mitigations are specified or required beyond applying the vendor-provided update.
CVE-2026-55653: Double Free in Red Hat Red Hat Enterprise Linux 10
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).
CVSS v3.1
Score 4.3medium
Affected software
Red Hat
Red Hat Enterprise Linux 10
Red Hat
Red Hat Enterprise Linux 8
Red Hat
Red Hat Enterprise Linux 9
Red Hat
Red Hat Hardened Images
Red Hat
Red Hat Update Infrastructure 5
Red Hat
Red Hat Update Infrastructure 5
Red Hat
Red Hat Update Infrastructure 5
Red Hat
Red Hat Update Infrastructure 5
Red Hat
Red Hat Enterprise Linux 6
Red Hat
Red Hat Enterprise Linux 7
Red Hat
Red Hat OpenShift Container Platform 4
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-55653 is a double free vulnerability in the OpenSSH client on Red Hat Enterprise Linux 10. It occurs during the Diffie-Hellman Group Exchange (DH-GEX) client path when operating in FIPS mode, specifically during known-group validation of DH-GEX parameters supplied by a malicious SSH server. Successful exploitation causes client-side process termination, leading to denial of service. Red Hat has published security advisories and released updated OpenSSH packages (version 10.3p1-6.hum1) that fix this vulnerability.
Potential Impact
The vulnerability allows a malicious SSH server to cause the OpenSSH client to crash by triggering a double free condition during DH-GEX group parameter validation in FIPS mode. This results in denial of service on the client side. There is no indication of confidentiality or integrity impact, and no known exploits in the wild have been reported.
Mitigation Recommendations
Red Hat has released updated OpenSSH packages (openssh-10.3p1-6.hum1) that fix this vulnerability. Users of Red Hat Enterprise Linux 10 should apply these official updates promptly to remediate the issue. Patch status is confirmed by Red Hat advisories. No additional mitigations are specified or required beyond applying the vendor-provided update.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-06-16T23:55:05.737Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-55653","vendor":"Red Hat"}]
Threat ID: 6a3a0366eed863c81e190b81
Added to database: 06/23/2026, 03:54:14 UTC
Last enriched: 08/13/2026, 13:37:51 UTC
Last updated: 09/21/2026, 22:01:35 UTC
Views: 152
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