CVE-2026-121549
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Insecure Temporary File Handling in nnn

Publication date: 2026-11-03

Last updated on: 2026-11-03

Assigner: VulnCheck

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.

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Meta Information

Published
2026-11-03
Last Modified
2026-11-03
Generated
2026-11-03
AI Q&A
2026-11-03
EPSS Evaluated
N/A
NVD
CVE-2026-121549
EUVD
EUVD-2026-115894

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
jarun nnn 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-377 Creating and using insecure temporary files can leave application and system data vulnerable to attack.

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Executive Summary

This vulnerability affects nnn versions up to 5.3 in the pdfread and nuke plugins. It involves insecure temporary file handling where predictable paths in /tmp allow local attackers to create symlinks. These symlinks can cause the plugins to overwrite any writable file accessible to the victim by exploiting the predictable file paths.

Detection Guidance

Check for vulnerable nnn versions (up to 5.3) by running 'nnn --version'. Inspect plugins like pdfread and nuke for insecure temporary file handling. Look for symlinks in /tmp pointing to predictable paths derived from filenames or PIDs.

Impact Analysis

An attacker with local access could overwrite critical system or user files, leading to data loss, corruption, or denial of service. Since the attack requires local access, the impact is limited to users who have local shell access on the affected system.

Mitigation Strategies

Update nnn to the latest version with security fixes. Remove vulnerable plugins (pdfread, nuke) if not updated. Monitor /tmp for suspicious symlinks and restrict write permissions to sensitive files.

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