CVE-2026-3731
Published: 08 March 2026
Summary
CVE-2026-3731 is a medium-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Libssh Libssh. Its CVSS base score is 6.9 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 13.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and CM-6 (Configuration Settings).
Deeper analysis
CVE-2026-3731 is an out-of-bounds read vulnerability in libssh versions up to and including 0.11.3. The issue resides in the SFTP Extension Name Handler component, specifically within the functions sftp_extensions_get_name and sftp_extensions_get_data in the file src/sftp.c. Manipulation of the argument idx triggers the out-of-bounds read.
A remote, unauthenticated attacker can exploit this vulnerability over the network with low attack complexity and no user interaction required. The CVSS v3.1 base score of 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) indicates no impact on confidentiality or integrity but a low impact on availability, potentially resulting in a denial of service such as an application crash. The vulnerability is associated with CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-125 (Out-of-bounds Read).
Advisories recommend upgrading to libssh version 0.11.4 or 0.12.0 to resolve the issue. The fixing patch, identified by commit 855a0853ad3abd4a6cd85ce06fce6d8d4c7a0b60, is available in the libssh GitLab repository, with source tarballs such as libssh-0.12.0.tar.xz provided for reference.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-10234
Vulnerability details
A weakness has been identified in libssh up to 0.11.3. The impacted element is the function sftp_extensions_get_name/sftp_extensions_get_data of the file src/sftp.c of the component SFTP Extension Name Handler. Executing a manipulation of the argument idx can lead to out-of-bounds read.…
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The attack may be performed from remote. Upgrading to version 0.11.4 and 0.12.0 is sufficient to resolve this issue. This patch is called 855a0853ad3abd4a6cd85ce06fce6d8d4c7a0b60. You should upgrade the affected component.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Out-of-bounds read in libssh SFTP handler enables remote unauthenticated crash (availability impact only), directly matching application/system exploitation for DoS.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires timely remediation of identified flaws such as the out-of-bounds read in libssh by applying the vendor patch (v0.11.4/0.12.0).
Enforces configuration settings that restrict use of vulnerable libssh versions through approved software baselines and version controls.
Requires vulnerability scanning to identify systems running the affected libssh versions (≤0.11.3) prior to exploitation.