CVE-2026-59857 Vim vulnerability
Vim is an open source, command line text editor. Prior to 9.2.0725, the single-byte branch of spell_soundfold_sal() in src/spell.c translates a word through a spell file's SAL sound-folding rules into a caller-owned result buffer, but its result writes are guarded with reslen < MAXWLEN, allowing reslen to reach MAXWLEN before res[reslen] = NUL writes one byte past the end of the MAXWLEN-element stack buffer. A boundary-length word passed to soundfold(), or reached via sound-based spell suggestion while a SAL-based spell language is active under a non-multibyte 8-bit encoding, can corrupt the eval_soundfold() stack frame and crash the editor. This issue is fixed in version 9.2.0725.
Quick answer
Vim should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Vim before 9.2.0725
Fixed versions
- 9.2.0725
How to fix it
CVE-2026-59857 affects Vim before 9.2.0725 where spell_soundfold_sal can write one byte past a stack buffer during SAL sound-folding, causing memory corruption or editor crash. Prioritize developer workstations, build hosts, jump boxes, and environments where users open untrusted source trees, spell files, or tags files. Upgrade Vim to 9.2.0725 or a later patched package from the OS vendor or upstream. Avoid untrusted spell files and SAL-based spell suggestion workflows until patched.
- Inventory Vim installations on developer workstations, servers, containers, CI images, jump hosts, and base images.
- Identify Vim versions before 9.2.0725 and determine whether the OS vendor package backports the relevant upstream patch.
- Upgrade Vim to 9.2.0725 or a later patched package, then rebuild affected base images and development containers.
- Avoid untrusted spell files and SAL-based spell suggestion workflows until patched.
- Reduce trust in project-local tags, completion scripts, modelines, spell files, and plugin-provided runtime files for repositories from untrusted sources.
- Review shell history, editor logs, endpoint telemetry, and suspicious project files for unexpected Ex commands, shell escapes, or crashes.
- If code execution is suspected, preserve the malicious project, rotate affected credentials, and rebuild compromised developer environments.
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Verify the fix
- Confirm vim --version or package metadata reports Vim 9.2.0725 or a vendor-patched later build.
- Confirm Vim patch level is 9.2.0725 or later and boundary-length SAL soundfold inputs do not crash the editor.
- Confirm patched completion or spell workflows handle crafted inputs without executing commands or corrupting memory.
- Rerun OS package, container, and endpoint vulnerability scans to confirm vulnerable Vim builds are gone.
- Document patched versions, rebuilt images, user guidance, and any incident evidence.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-59857?
Vim versions listed as affected should be reviewed: Vim before 9.2.0725.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.