Buffer overflow in Zlib
CVE-2026-22184
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (33.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000
Affected products
- Zlib
- Zlib Software — versions 0
Weakness classification (CWE)
References
- seclists.org/fulldisclosure/2026/Jan/3 (technical-description, Mailing List, Third Party Advisory, exploit)
- zlib.net/ (Product, product)
- github.com/madler/zlib (Product, product)
- www.vulncheck.com/advisories/zlib-untgz-global-buffer-overflow-in-tgzfname (Third Party Advisory, third-party-advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Issue Tracking)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Frequently asked questions
- What is CVE-2026-22184?
- CVE-2026-22184 is a high-severity vulnerability in Zlib, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2026-01-07.
- How severe is CVE-2026-22184?
- High severity. CVSS v3 base score is 7.8 out of 10.