# CVE-2026-23879: py7zr: Arbitrary File Write Vulnerability

> Attackers can write arbitrary files outside the extraction directory via malicious symbolic links, potentially leading to code execution or privilege escalation.

- **Severity:** High 8.0 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 25 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-23879, GHSA-q6rc-2cgv-63h7, PYSEC-2026-2974, UBUNTU-CVE-2026-23879

## What is CVE-2026-23879?

CVE-2026-23879 is a high-severity path traversal vulnerability in miurahr py7zr, published on 24 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Versions 1.1.2 and below contain an an arbitrary file write vulnerability, which allows symbolic links to be recreated outside the destination directory via crafted malicious symbolic link chains. When using extractall to extract an archive, the library restores these symbolic links, linking them to arbitrary directories on the host file system. During extraction, the program only checks the link arcname within the destination directory, but ignores the combined symlink path resolution. Attackers can exploit this vulnerability by constructing malicious archives, thereby bypassing the directory boundary restrictions implemented by the extractor. Subsequent extraction of regular files through these symbolic links can result in arbitrary file writes. This vulnerability may lead to remote code execution, privilege escalation, data corruption, or denial of service. This issue has been fixed in version 1.1.3.

Weakness: CWE-59 (Improper Link Resolution Before File Access)

## Which versions are affected by CVE-2026-23879?

3 open source packages ship an affected version, including py7zr.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `py7zr` | PyPI | All versions | 1.1.3 |
| `py7zr` | PyPI | All versions | 1.1.3 |
| `py7zr` | PyPI | All versions | 1.1.3 |

## How do I fix CVE-2026-23879?

Upgrade py7zr to 1.1.3 or later.

## Is CVE-2026-23879 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-23879 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23879 and fix it if it is affected.

What it is: CVE-2026-23879 is a high-severity path traversal vulnerability in miurahr py7zr, published on 24 Jun 2026. Any signed-in user can exploit it over the 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-2026-23879 exists.

Affected packages and fixed versions:
- py7zr (PyPI): affected all versions; fixed in 1.1.3
- py7zr (PyPI): affected all versions; fixed in 1.1.3
- py7zr (PyPI): affected all versions; fixed in 1.1.3

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-2026-23879/ (Markdown: https://insights.sbomify.com/CVE-2026-23879/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23879
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23879
- OSV: https://osv.dev/vulnerability/CVE-2026-23879

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-23879/
Summaries are generated and may contain mistakes; the official description above is the record.