CVE-2026-65610
Received Received - Intake

Out-of-Bounds Read/Write in nnn File Manager

Publication date: 2026-08-19

Last updated on: 2026-08-19

Assigner: CERT.PL

Description
nnn stores homelen variable as uchar_t, which can only represent values in the range 0-255. An attacker who can influence the victim's execution environment can provide an arbitrary HOME path with length that is truncated to 0. The expression (homelen - 1) is promoted to signed int and becomes -1 and producing an out-of-bounds read and an out-of-bounds write one byte before the path buffer.  Maintainer of this project was notified about this vulnerability. It might has been addressed, but the maintainer did not provide a vulnerable version range. Only version 5.2 was tested and confirmed as vulnerable.

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Meta Information

Published
2026-08-19
Last Modified
2026-08-19
Generated
2026-08-19
AI Q&A
2026-08-19
EPSS Evaluated
N/A
NVD
CVE-2026-65610
EUVD
EUVD-2026-62399

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-197 Truncation errors occur when a primitive is cast to a primitive of a smaller size and data is lost in the conversion.

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Executive Summary

CVE-2026-65610 is a numeric truncation error in nnn software version 5.2. The homelen variable is stored as an unsigned char (0-255 range). An attacker can provide a HOME path longer than 255 characters, causing the length to truncate to 0. This makes (homelen - 1) evaluate to -1, leading to out-of-bounds read and write operations one byte before the path buffer.

Detection Guidance

To detect this vulnerability, check if nnn version 5.2 is installed and monitor for unusual memory access patterns or crashes when processing HOME environment variables with long paths. Examine logs for out-of-bounds read/write errors near path buffers.

Impact Analysis

An attacker who can influence your execution environment could exploit this to cause memory corruption, crash the program, or potentially execute arbitrary code. This requires the attacker to control the HOME environment variable path length.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR or HIPAA as it is a low-severity memory corruption issue in the nnn software. However, if exploited, it could lead to memory corruption which might indirectly impact data integrity or confidentiality, potentially affecting compliance in environments where nnn is used for file management.

Mitigation Strategies

Upgrade nnn to a patched version if available. Avoid using untrusted HOME environment variables. Restrict user permissions to limit environment manipulation. Monitor for suspicious activity in memory access.

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