# CVE-2026-65610: Numeric Truncation Error in nnn

> An attacker can trigger an out-of-bounds read and write in nnn by providing a long HOME path, potentially leading to code execution or crashes.

- **Severity:** Low 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 19 Aug 2026
- **Updated:** 20 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-65610, GHSA-2fq9-p2vj-rc2v, UBUNTU-CVE-2026-65610

## What is CVE-2026-65610?

CVE-2026-65610 is a low-severity vulnerability in nnn, published on 19 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-197 (Numeric Truncation Error)

## Which versions are affected by CVE-2026-65610?


## How do I fix CVE-2026-65610?

No fix has been published for CVE-2026-65610 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-65610 being exploited?

There is no known exploitation of CVE-2026-65610 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-65610 and fix it if it is affected.

What it is: CVE-2026-65610 is a low-severity vulnerability in nnn, published on 19 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-65610 in the wild and no public exploit code.

Affected product: nnn. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-65610/ (Markdown: https://insights.sbomify.com/CVE-2026-65610/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-65610
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-65610
- OSV: https://osv.dev/vulnerability/CVE-2026-65610

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-65610/
Summaries are generated and may contain mistakes; the official description above is the record.