CVE-2026-59847
Received Received - Intake

Incorrect AES-GCM Integrity Bypass in libssh

Publication date: 2026-07-21

Last updated on: 2026-07-21

Assigner: Red Hat, Inc.

Description
A flaw was found in libssh. Incorrect AES-GCM finalization checks in builds using the OpenSSL backend can effectively remove integrity protection, allowing an in-path attacker to modify plaintext on the wire without detection.

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Meta Information

Published
2026-07-21
Last Modified
2026-07-21
Generated
2026-07-21
AI Q&A
2026-07-21
EPSS Evaluated
N/A
NVD
CVE-2026-59847
EUVD
EUVD-2026-46255

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
libssh libssh *
libssh libssh to 2026-07-08 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-1310 Missing an ability to patch ROM code may leave a System or System-on-Chip (SoC) in a vulnerable state.

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Executive Summary

This vulnerability is in libssh when using the OpenSSL backend for AES-GCM encryption. The flaw occurs during decryption in src/libcrypto.c where the return value from EVP_DecryptFinal() is incorrectly checked. This causes authentication tag verification failures to be treated as non-integrity issues, removing integrity protection for AES-GCM sessions.

Detection Guidance

To detect this vulnerability, inspect libssh versions using package managers like 'rpm -qa | grep libssh' or 'dpkg -l | grep libssh'. Check for OpenSSL backend usage in libssh configurations. Monitor network traffic for unexpected plaintext modifications during AES-GCM encrypted sessions.

Impact Analysis

An attacker in the network path could modify plaintext data during transmission without detection. This could lead to unauthorized changes in sensitive communications or data transfers.

Compliance Impact

This vulnerability could compromise data integrity, which is a key requirement for GDPR and HIPAA compliance. Unauthorized data modification could lead to violations of these regulations, potentially resulting in legal and financial penalties.

Mitigation Strategies

Update libssh to the latest patched version to ensure proper AES-GCM integrity checks are in place. If using OpenSSL backend, verify the library version and apply security patches from your vendor.

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