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CVE-2024-3094: XZ Utils backdoor

Embedded Malicious Code: Is CVE-2024-3094 real, exploitable, or a false positive? Here's the community verdict.

signals

public sources

Exploited in wild
Not listed
CISA KEV
Public exploit
PoC (unverified)
Metasploit/EDB/PoC
Base severity
10 Critical
CVSS
Exploitation prob.
86%
FIRST EPSS
Weakness
CWE-506 · Embedded Malicious Code
CWE

High severity and high exploitation probability. Prioritise remediation.

public exploits

links to sources — we don’t host code

Unverified proof-of-concept code has been published. It may or may not be functional — assess before relying on it.

baseline read

auto · not a community verdict

Likely real & worth prioritising

High base severity and a high real-world exploitation probability both point to a genuine, actively targeted issue.

Based on CVSS · FIRST EPSS

Confirm or dispute →

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Malicious code was discovered in the upstream tarballs of xz, starting with version 5.6.0. Through a series of complex obfuscations, the liblzma build process extracts a prebuilt object file from a disguised test file existing in the source code, which is then used to modify specific functions in the liblzma code. This results in a modified liblzma library that can be used by any software linked against this library, intercepting and modifying the data interaction with this library.

Published

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In your experience, is this finding real and exploitable?

awaiting field verdicts
Real, but not a risk here
Not a real issue

Curated baseline: TruePositive's read from public sources is Real, needs specific conditions — a starting point, not a community verdict.

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Field notes & remediation

Verdicts are the quick signal. Notes are the evidence and fixes behind them.

  • 0
    Field note · TruePositive EditorialCurated

    This is a real backdoor, but for most companies the scanner alert does not apply. A malicious maintainer hid a backdoor in xz/liblzma versions 5.6.0 and 5.6.1. On some systems it hooks into sshd and lets one specific attacker (who holds a secret key) log in without a password. This is a targeted, government-level backdoor, not a mass attack.

    Who was actually affected: only bleeding-edge or rolling distros around March 2024. That means Fedora 40 and Rawhide, Debian sid and testing, openSUSE Tumbleweed, Kali (for a short time), and Arch. Stable production systems like RHEL, Ubuntu LTS, Debian stable, and Amazon Linux shipped version 5.4.x and were never affected. It was found early (by Andres Freund) before it reached stable releases, so very few systems were hit.

    So if your scanner flags xz 5.6.0 or 5.6.1, first check your distro. If it is a stable release, you are almost certainly not applicable. If it is rolling or beta, run xz --version, run the public detection script against liblzma, and check whether your sshd is even linked to liblzma in the vulnerable way.

    Commonly flagged by: Trivy, Grype, Dependabot, OSV-Scanner.

  • 0
    Remediation · TruePositive EditorialCurated

    Downgrade xz/liblzma to a safe 5.4.x version, or use your distro's fixed build (or 5.8+). If a system actually ran 5.6.0 or 5.6.1 with the vulnerable sshd link, treat it as possibly compromised. Rebuild it from clean sources, rotate SSH host keys and any secrets on that machine, and review access logs. If you were on a stable distro the whole time, you only need to confirm your version.

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Same weakness: CWE-506 · Embedded Malicious Code.