VulnerableCode Package Details - pkg:gem/zlib@3.1.1

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Vulnerability	Summary	Fixed by
VCID-sfzh-hn56-hbak Aliases: CVE-2026-27820 GHSA-g857-hhfv-j68w	Buffer overflow vulnerability in Zlib::GzipReader A buffer overflow vulnerability exists in Zlib::GzipReader. This vulnerability has been assigned the CVE identifier CVE-2026-27820. We recommend upgrading the zlib gem. ## Details 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. ## Recommended action We recommend to update the zlib gem to version 3.2.3 or later. In order to ensure compatibility with bundled version in older Ruby series, you may update as follows instead: * For Ruby 3.2 users: Update to zlib 3.0.1 * For Ruby 3.3 users: Update to zlib 3.1.2 * You can use gem update zlib to update it. If you are using bundler, please add gem "zlib", ">= 3.2.3" to your Gemfile. ## Affected versions: zlib gem 3.2.2 or lower ## Credits Thanks to calysteon for reporting this issue. Also thanks to nobu for creating the patch.	3.1.2 Affected by 0 other vulnerabilities. 3.2.3 Affected by 0 other vulnerabilities.

Vulnerability

Summary

Fixed by

VCID-sfzh-hn56-hbak
Aliases:
CVE-2026-27820
GHSA-g857-hhfv-j68w

Buffer overflow vulnerability in Zlib::GzipReader A buffer overflow vulnerability exists in Zlib::GzipReader. This vulnerability has been assigned the CVE identifier CVE-2026-27820. We recommend upgrading the zlib gem. ## Details 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. ## Recommended action We recommend to update the zlib gem to version 3.2.3 or later. In order to ensure compatibility with bundled version in older Ruby series, you may update as follows instead: * For Ruby 3.2 users: Update to zlib 3.0.1 * For Ruby 3.3 users: Update to zlib 3.1.2 * You can use gem update zlib to update it. If you are using bundler, please add gem "zlib", ">= 3.2.3" to your Gemfile. ## Affected versions: zlib gem 3.2.2 or lower ## Credits Thanks to calysteon for reporting this issue. Also thanks to nobu for creating the patch.

3.1.2
Affected by 0 other vulnerabilities.

3.2.3
Affected by 0 other vulnerabilities.

Vulnerability	Summary	Aliases
This package is not known to fix vulnerabilities.

Vulnerability

Summary

Aliases

This package is not known to fix vulnerabilities.

Date	Actor	Action	Vulnerability	Source	VulnerableCode Version
2026-04-16T17:41:45.569828+00:00	Ruby Importer	Affected by	VCID-sfzh-hn56-hbak	https://github.com/rubysec/ruby-advisory-db/blob/master/gems/zlib/CVE-2026-27820.yml	38.4.0
2026-04-11T21:39:51.322308+00:00	Ruby Importer	Affected by	VCID-sfzh-hn56-hbak	https://github.com/rubysec/ruby-advisory-db/blob/master/gems/zlib/CVE-2026-27820.yml	38.3.0
2026-04-02T19:37:11.638422+00:00	Ruby Importer	Affected by	VCID-sfzh-hn56-hbak	https://github.com/rubysec/ruby-advisory-db/blob/master/gems/zlib/CVE-2026-27820.yml	38.1.0
2026-04-01T15:55:00.122080+00:00	Ruby Importer	Affected by	VCID-sfzh-hn56-hbak	https://github.com/rubysec/ruby-advisory-db/blob/master/gems/zlib/CVE-2026-27820.yml	38.0.0