Numeric Truncation Error in nnn

published 2026-08-19 2 mo ago modified 2026-10-27 12 d ago also EUVD-2026-62399

cvss: 2.4; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits: 0; none known

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.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-65610 updated 2026-08-24 cvss 4.8

nnn: nnn: Out-of-bounds read and write via numeric truncation error

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 mo ago (2026-08-20)

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	2.4	CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
CNA	4.0	2.4	CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:L/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

Affected products

nnn nnn

Classification

Weakness

CWE-197 Numeric Truncation Error

References

cert.pl /en/posts/2026/08/CVE-2026-65609
third-party-advisory

Sources

CVE List CVE-2026-65610
NVD CVE-2026-65610

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Summary