CVE-2026-27820

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.

CVSS

No CVSS.

References

Link	Resource
https://github.com/ruby/zlib/security/advisories/GHSA-g857-hhfv-j68w
https://hackerone.com/reports/3467067

Configurations

No configuration.

History

16 Apr 2026, 18:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-16 18:16

Updated : 2026-04-17 15:38

NVD link : CVE-2026-27820

Mitre link : CVE-2026-27820

CVE.ORG link : CVE-2026-27820

JSON object : View

Products Affected

No product.

CWE

CWE-120

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CWE-131

Incorrect Calculation of Buffer Size

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