CVE-2026-27820
Ruby vulnerability analysis and mitigation

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.


SourceNVD

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CVE ID

Severity

Score

Technologies

Component name

CISA KEV exploit

Has fix

Published date

GHSA-2x79-gwq3-vxxmHIGH8.7
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NoNoApr 14, 2026
CVE-2026-41146HIGH8.7
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GHSA-3jfp-46x4-xgfjMEDIUM6.9
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CVE-2026-27820LOW1.7
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  • ruby3.1
NoYesApr 16, 2026

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