REDHAT-BUG-2383888: Low severity libssh libssh vulnerability

Published Jul 28, 2025
·
Updated

Memory Exhaustion vulnerability in the key exchange logic of the libssh library. When an authenticated client repeatedly performs rekeying with incorrect firstkexpacketfollows guesses, libssh allocates new ephemeral key pairs without freeing old ones stored in session->nextcrypto. Over time, this results in a memory leak that can exhaust system memory and cause a client-side denial-of-service (DoS). This flaw affects several KEX algorithms (Curve25519, ECDH, sntrup761x25519, DH-GEX) across multiple crypto backends (libgcrypt, OpenSSL, mbedTLS). The issue requires an authenticated client and does not impact the server side. Versions Affected : libssh >= 0.6.0

Affected Software

1 affected component
libssh libssh>=0.6.0

Event History

Jul 28, 2025
Data Sourced
via Red Hat·11:06 AM
DescriptionSeverityAffected Software
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Frequently Asked Questions

1

What is the severity of REDHAT-BUG-2383888?

The severity of REDHAT-BUG-2383888 is classified as high due to potential memory exhaustion issues.

2

How do I fix REDHAT-BUG-2383888?

To fix REDHAT-BUG-2383888, update the libssh library to a version higher than 0.6.0 where the vulnerability has been addressed.

3

What systems are affected by REDHAT-BUG-2383888?

REDHAT-BUG-2383888 affects systems using libssh versions starting from 0.6.0 and higher.

4

What is the impact of REDHAT-BUG-2383888 if exploited?

If exploited, REDHAT-BUG-2383888 can lead to memory exhaustion, potentially causing service disruptions.

5

Is there a workaround for REDHAT-BUG-2383888?

Currently, there are no official workarounds for REDHAT-BUG-2383888 besides updating the affected library.

Contact

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