CVE-2026-22184

zlib <= 1.3.1.2 untgz Global Buffer Overflow in TGZfname()

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Published Jan 7, 2026 CVSS 4.0 · 4.6 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

 cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}
Type Values Removed Values Added
Description zlib versions up to and including 1.3.1.2 contain a global buffer overflow in the untgz utility. The TGZfname() function copies an attacker-supplied archive name from argv[] into a fixed-size 1024-byte static global buffer using an unbounded strcpy() call without length validation. Supplying an archive name longer than 1024 bytes results in an out-of-bounds write that can lead to memory corruption, denial of service, and potentially code execution depending on compiler, build flags, architecture, and memory layout. The overflow occurs prior to any archive parsing or validation. 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.
Metrics cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

 cvssV4_0

{'score': 4.6, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N'}
Type Values Removed Values Added
Weaknesses CWE-787
CPEs cpe:2.3:a:zlib:zlib:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 8.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H'}

 cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}
Type Values Removed Values Added
References
Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 8.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H'}

threat_severity

Important
Type Values Removed Values Added
First Time appeared Zlib
Zlib zlib
Vendors & Products Zlib
Zlib zlib
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}
Type Values Removed Values Added
Description zlib versions up to and including 1.3.1.2 contain a global buffer overflow in the untgz utility. The TGZfname() function copies an attacker-supplied archive name from argv[] into a fixed-size 1024-byte static global buffer using an unbounded strcpy() call without length validation. Supplying an archive name longer than 1024 bytes results in an out-of-bounds write that can lead to memory corruption, denial of service, and potentially code execution depending on compiler, build flags, architecture, and memory layout. The overflow occurs prior to any archive parsing or validation.
Title zlib <= 1.3.1.2 untgz Global Buffer Overflow in TGZfname()
Weaknesses CWE-120
References
Metrics cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}
Earlier changes (3)
Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 1, 2026, 12:04 PM
Reserved
Jan 6, 2026, 4:47 PM

View source JSON

Updated
Jan 12, 2026, 8:01 AM

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Status
Modified
Published
Jan 7, 2026, 9:16 PM
Modified
Sep 1, 2026, 1:18 PM

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Severity
Important
Public date
Jan 7, 2026, 8:25 PM

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Updated
Apr 16, 2026, 6:30 PM

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