# CVE-2026-121550: nnn through 5.3 Symlink-Following Write via NNN_FIFO Handling

Status: published. Published: 2026-11-03. Updated: 2026-11-09.

nnn through 5.3 contains an insecure file handling vulnerability that allows local attackers to redirect writes because main() accepts an existing NNN_FIFO path without verifying it is a FIFO. Attackers can pre-create the documented predictable /tmp/nnn.fifo path as a symlink or readable regular file, causing victim-writable files to be overwritten or leaking the victim's browsed paths.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/jarun/nnn/commit/04715921aece0257fef7a8558c0783493d98efff

## Affected products and versions

- jarun / nnn: ≥ 0; ≤ 5.3 (affected, custom). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 1 (low); CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 3.3 (low); CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 1 (low); CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 3.3 (low); CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.12% as of 2026-11-09; percentile 1.62%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-59

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/jarun/nnn/issues/2188 (CNA: VulnCheck; issue-tracking)

- https://github.com/jarun/nnn (CNA: VulnCheck; product)

- https://github.com/jarun/nnn/commit/04715921aece0257fef7a8558c0783493d98efff (CNA: VulnCheck; patch)

- https://github.com/jarun/nnn/blob/v5.3/src/nnn.c#L10635 (CNA: VulnCheck; technical-description)

- https://github.com/jarun/nnn/blob/v5.3/src/nnn.c#L7433 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/nnn-through-5.3-symlink-following-write-via-nnn-fifo-handling (CNA: VulnCheck; third-party-advisory)

- https://github.com/jarun/nnn (disclosure@vulncheck.com)

- https://github.com/jarun/nnn/blob/v5.3/src/nnn.c#L10635 (disclosure@vulncheck.com)

- https://github.com/jarun/nnn/blob/v5.3/src/nnn.c#L7433 (disclosure@vulncheck.com)

- https://github.com/jarun/nnn/commit/04715921aece0257fef7a8558c0783493d98efff (disclosure@vulncheck.com)

- https://github.com/jarun/nnn/issues/2188 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/nnn-through-5.3-symlink-following-write-via-nnn-fifo-handling (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-121550; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121550; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-121550; retrieved 2026-11-09; source updated Not reported

Revision: 3321ca89d226cdd5566eb20a770179ba1488b571e40e85240471327c6c776c47

Canonical: https://y2.dev/cve/CVE-2026-121550

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