CVE-2026-90954 Busybox: busybox: dpkg-deb extraction-root escape via per-ar-member deferred symlink flush
An attacker can write arbitrary files outside the extraction directory by crafting a malicious .deb archive exploiting symlink handling in BusyBox.
- 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
- None listed
What is CVE-2026-90954?
CVE-2026-90954 is a high-severity path traversal vulnerability in Red Hat Hardened Images, published on 14 Oct 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
A flaw was found in BusyBox's dpkg-deb archive extraction. The ar archive handler flushes deferred symlinks after each archive member, unlike the tar, cpio, and unzip handlers which flush once after the last member. A specially crafted .deb archive with two data.tar members can exploit this ordering: the first member declares a symlink pointing to an absolute path (e.g., '/'), which is deferred as unsafe but flushed after the first member. The second member declares a regular file whose path traverses the now-live symlink, resulting in a file being written outside the intended extraction directory. This could allow an attacker to write arbitrary files to arbitrary locations when a user extracts a crafted .deb package.
Weakness: CWE-59
Which versions are affected by CVE-2026-90954?
How do I fix CVE-2026-90954?
No fix has been published for CVE-2026-90954 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-90954 being exploited?
There is no known exploitation of CVE-2026-90954 in the wild and no public exploit code.
Sources
Also known as AZL-109776, DEBIAN-CVE-2026-90954, GHSA-68qr-37mv-cwhv, UBUNTU-CVE-2026-90954.