CVE-2026-51400: 
Vim vulnerability analysis and mitigation

CVE-2026-51400 is a memory leak vulnerability in the Vim text editor (v9.2.0389 and earlier) that allows a local attacker to execute arbitrary code via the vms_fixfilename() function within vim/src/os_vms.c. The vulnerability was discovered by XiJie Ao of B429 Laboratory, Wuhan University, and publicly disclosed on August 4, 2026. It carries a CVSS v3.1 base score of 8.4 (High), assigned by CISA-ADP (Github Advisory, Security Advisory Gist).

The root cause is classified as CWE-401 (Missing Release of Memory after Effective Lifetime): a static heap buffer allocated within vms_fixfilename() in src/os_vms.c is never freed during the Vim process lifetime. Repeated invocations — such as during long editing sessions or automated file processing — cause continuous memory accumulation, which in extreme cases leads to resource exhaustion. The advisory also associates CWE-94 (Code Injection) with this CVE, suggesting that the memory mismanagement condition may be leveraged by a local attacker to achieve arbitrary code execution, though the precise exploitation mechanism beyond memory exhaustion is not fully detailed in public sources. No user interaction or elevated privileges are required for exploitation (Security Advisory Gist, Github Advisory).

Successful exploitation could result in high confidentiality, integrity, and availability impact on the affected system, as reflected in the CVSS score. A local attacker can trigger arbitrary code execution with the privileges of the Vim process, potentially enabling unauthorized data access, modification, or denial of service through resource exhaustion. The vulnerability is limited to local attack vectors and does not affect Vim instances running on non-VMS platforms, as the vulnerable code resides in the VMS-specific os_vms.c file (Security Advisory Gist, Red Hat Bugzilla).

There is currently no public proof-of-concept exploit or evidence of in-the-wild exploitation for CVE-2026-51400. CISA's SSVC assessment notes exploitation status as "none" and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS score is approximately 0.124% (3rd percentile), indicating a low near-term exploitation probability (Github Advisory, Security Advisory Gist).

Users should update Vim to a version later than v9.2.0389, which resolves the memory management issue in vms_fixfilename(). As an interim measure, administrators should restrict local access to systems running vulnerable Vim versions and monitor for unusual memory consumption by Vim processes. A patch has been confirmed available per the GitHub Advisory and Red Hat Bugzilla tracking (Github Advisory, Red Hat Bugzilla).

Red Hat has opened a tracking bug (Bug 2511268) for this CVE with medium priority and severity, indicating it is being assessed for impact on Red Hat products. No significant public researcher commentary or broader media coverage has been identified at this time (Red Hat Bugzilla).