# CVE-2026-45380: bit7z: Path Traversal via Null Byte Injection from `gcount()` Off-by-One in `restoreSymlink()`

> Attackers can craft malicious archives to create symlinks and write arbitrary files outside the extraction directory via an off-by-one error.

- **Severity:** Low 3.6 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 10 Jun 2026
- **Updated:** 11 Jun 2026
- **Also known as:** GHSA-8wj8-9jwv-j24v

## What is CVE-2026-45380?

CVE-2026-45380 is a low-severity path traversal vulnerability in rikyoz bit7z, published on 10 Jun 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

bit7z is a cross-platform C++ static library that allows the compression/extraction of archive files. Prior to version 4.0.12, a one-byte off-by-one error in SafeOutPathBuilder::restoreSymlink() allows an attacker to craft a .7z archive that, when extracted with bit7z on any non-Windows platform, creates a symlink escaping the intended output directory. Subsequent archive entries extracted through this symlink write arbitrary files outside the extraction directory with the permissions of the extracting process. This issue has been patched in version 4.0.12.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), CWE-193 (Off-by-one Error)

## Which versions are affected by CVE-2026-45380?


## How do I fix CVE-2026-45380?

No fix has been published for CVE-2026-45380 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-45380 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45380 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45380 and fix it if it is affected.

What it is: CVE-2026-45380 is a low-severity path traversal vulnerability in rikyoz bit7z, published on 10 Jun 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45380 exists.

Affected product: rikyoz bit7z. 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-2026-45380/ (Markdown: https://insights.sbomify.com/CVE-2026-45380/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45380
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45380
- OSV: https://osv.dev/vulnerability/CVE-2026-45380

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45380/
Summaries are generated and may contain mistakes; the official description above is the record.