Incorrect Calculation of Buffer Size Affecting ruby4.0 package, versions <0:4.0.0-33.3.hum1


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (13th percentile)

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  • Snyk IDSNYK-RHEL10-RUBY40-16094391
  • published19 Apr 2026
  • disclosed16 Apr 2026

Introduced: 16 Apr 2026

NewCVE-2026-27820  (opens in a new tab)
CWE-131  (opens in a new tab)

How to fix?

Upgrade RHEL:10 ruby4.0 to version 0:4.0.0-33.3.hum1 or higher.
This issue was patched in RHSA-2026:8838.

NVD Description

Note: Versions mentioned in the description apply only to the upstream ruby4.0 package and not the ruby4.0 package as distributed by RHEL. See How to fix? for RHEL:10 relevant fixed versions and status.

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 Base Scores

version 3.1