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ZlibApplication

CVE-2026-22184

HIGH · 7.8 CVSS v3.1 Published 2026-01-07
Fix available
A fix is available. Upgrade to after 1.3.1.2 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
zlib versions up to and including 1.3.1.2 include a global buffer overflow in the untgz utility located under contrib/untgz. The vulnerability is limited to the standalone demonstration utility and does not affect the core zlib compression library. The flaw occurs when a user executes the untgz command with an excessively long archive name supplied via the command line, leading to an out-of-bounds write in a fixed-size global buffer.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A global buffer overflow exists in the untgz demonstration utility (contrib/untgz) of zlib versions up to 1.3.1.2. The vulnerability is triggered when a user provides an excessively long archive name via command line, causing an out-of-bounds write to a fixed-size global buffer. This affects only the standalone demo utility, not the core zlib compression library.

MitigationSince untgz is a demonstration utility only, the primary remediation is to avoid using it in production environments. If currently deployed, remove or disable the utility until an official patch is released. The core zlib library remains unaffected.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
ZlibApplication
Affected:<= 1.3.1.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate the untgz utility
    Search for the untgz binary or script in common locations such as /usr/bin/untgz, /usr/local/bin/untgz, or within the zlib source contrib/untgz directory. Use: find / -name 'untgz' -type f 2>/dev/null
    Affected if The untgz demonstration utility exists in the environment
  2. Identify the zlib version
    Run 'zlib-flate -version' or check the version header at /usr/include/zlib.h or /usr/local/include/zlib.h. Look for the ZLIB_VERSION macro value
    Affected if The installed zlib version is 1.3.1.2 or earlier
  3. Confirm untgz is from the same zlib installation
    Run 'untgz --help' or check the binary metadata to verify it was built with the affected zlib version. Compare the version found in step 2
    Affected if untgz was compiled against zlib version 1.3.1.2 or earlier
  4. Verify the attack surface
    Determine if untgz processes archive filenames from untrusted sources, as the overflow is triggered by excessively long archive filenames provided via command line
    Affected if untgz is used with user-supplied or untrusted archive filenames

A user is affected only if they have the untgz demonstration utility present AND it is built from zlib version 1.3.1.2 or earlier AND they use it with potentially long archive filenames from untrusted sources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 1.3.1.2
Interim mitigation

Since untgz is a demonstration utility only, the primary remediation is to avoid using it in production environments. If currently deployed, remove or disable the utility until an official patch is released. The core zlib library remains unaffected.

Recommended fix High confidence

zlib 1.3.1.3 or later

  1. 1. Identify all systems with zlib installed that have the untgz utility (located in contrib/untgz/)
  2. 2. Check the current zlib version on affected systems using 'zlib-flate -version' or by inspecting the source
  3. 3. Download the latest zlib release from the official zlib source (zlib.net) or GitHub repository
  4. 4. Upgrade zlib to version 1.3.1.3 or later which contains the fix for the untgz buffer overflow
  5. 5. Verify the upgrade was successful by checking the zlib version
  6. 6. Rebuild any applications that link against zlib if necessary
Caveat The untgz utility is a standalone demo tool; upgrading zlib core library may require recompiling dependent applications if ABI compatibility is a concern

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zlib Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-22184 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data