Is there a patch available for CVE-2026-27820?

Yes, a patch is available for CVE-2026-27820. Update the affected software to the latest version immediately.

Zlib CVE-2026-27820

Q: What is the CVSS score of CVE-2026-27820?

CVE-2026-27820 has a CVSS 4.0 base score of 1.7 (Low). CVSS vector: 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. EPSS exploitation probability: 0.0%.

EUVD-2026-23278 LOW

Classic Buffer Overflow (CWE-120)

2026-04-16 GitHub_M

GHSA-g857-hhfv-j68w

Buffer Overflow Zlib

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

Lifecycle Timeline

Patch released

Apr 17, 2026 - 15:38 nvd

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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CVE-2026-27820 vulnerability details – vuln.today

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