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Zlib EUVD-2026-23278

| CVE-2026-27820 LOW
Classic Buffer Overflow (CWE-120)
2026-04-16 GitHub_M GHSA-g857-hhfv-j68w
1.7
CVSS 4.0 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY
1.7 LOW
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

5
Patch released
Apr 17, 2026 - 15:38 nvd
Patch available
Patch available
Apr 16, 2026 - 19:16 EUVD
CVSS changed
Apr 16, 2026 - 18:22 NVD
1.7 (LOW)
EUVD ID Assigned
Apr 16, 2026 - 18:00 euvd
EUVD-2026-23278
CVE Published
Apr 16, 2026 - 17:27 nvd
LOW 1.7

DescriptionGitHub Advisory

zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. The zstream_buffer_ungets function prepends caller-provided bytes ahead of previously produced output but fails to guarantee the backing Ruby string has enough capacity before the memmove shifts the existing data. This can lead to memory corruption when the buffer length exceeds capacity. This issue has been fixed in versions 3.0.1, 3.1.2 and 3.2.3.

Analysis

zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. …

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EUVD-2026-23278 vulnerability details – vuln.today

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