Medium severity · published Feb 18, 2026
CVE-2026-27171
zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition
5.5
CVSS
0.2%
EPSS
No
On KEV
Description
zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 16% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ZL
zlib · zlib
before 1.3.2 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27171
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27171
Product
https://7asecurity.com/blog/2026/02/zlib-7asecurity-audit/
Technical Description
https://7asecurity.com/reports/pentest-report-zlib-RC1.1.pdf
Exploit
https://github.com/madler/zlib/issues/904
Release Notes
https://github.com/madler/zlib/releases/tag/v1.3.2
Product
https://ostif.org/zlib-audit-complete/
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