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.
History

Sat, 24 Oct 2026 05:45:00 +0000

Type Values Removed Values Added
First Time appeared Busybox
Busybox busybox
Redhat hardened Images
Vendors & Products Busybox
Busybox busybox
Redhat hardened Images

Mon, 19 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Wed, 14 Oct 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Wed, 14 Oct 2026 10:15:00 +0000

Type Values Removed Values Added
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.
Title Busybox: busybox: dpkg-deb extraction-root escape via per-ar-member deferred symlink flush
First Time appeared Redhat
Redhat hummingbird
Weaknesses CWE-59
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published: 2026-10-14T10:00:08.215Z

Updated: 2026-10-19T19:04:36.467Z

Reserved: 2026-09-14T11:58:18.067Z

Link: CVE-2026-90954

cve-icon Vulnrichment

Updated: 2026-10-19T19:04:30.627Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-14T10:17:57.297

Modified: 2026-10-19T20:21:10.970

Link: CVE-2026-90954

cve-icon Redhat

Severity : Important

Publid Date: 2026-10-14T08:00:00Z

Links: CVE-2026-90954 - Bugzilla