CVE-2026-27117

What it is

bit7z is a cross-platform C++ static library that allows the compression/extraction of archive files. Prior to version 4.0.11, a path traversal vulnerability ("Zip Slip") exists in bit7z's archive extraction functionality. The library does not adequately validate file paths contained in archive entries, allowing files to be written outside the intended extraction directory through three distinct mechanisms: relative path traversal, absolute path traversal, and symbolic link traversal. An attacker can exploit this by providing a malicious archive to any application that uses bit7z to extract untrusted archives. Successful exploitation results in arbitrary file write with the privileges of the process performing the extraction. This could lead to overwriting of application binaries, configuration files, or other sensitive data. The vulnerability does not directly enable reading of file contents; the confidentiality impact is limited to the calling application's own behavior after extraction. However, applications that subsequently serve or display extracted files may face secondary confidentiality risks from attacker-created symlinks. Fixes have been released in version 4.0.11. If upgrading is not immediately possible, users can mitigate the vulnerability by validating each entry's destination path before writing. Other mitigations include running extraction with least privilege and extracting untrusted archives in a sandboxed directory.

At a glance

Exploitability

Can be exploited locally on the machine without logging in, but needs a user to act. High risk of data tampering.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-02-24 22:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 10:26 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 5.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-02-24 22:16 UTC

Last modified

2026-06-17 10:26 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Analyzed

Affected

• Rikyoz bit7z < 4.0.11

Attack profile CVSS 3.1 · 5.5

Attack vector

Local

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-27117.md and follow it. Check whether this project is affected by CVE-2026-27117. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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