CVE-2026-27820

Publication date 16 April 2026

Last updated 6 November 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

9.8 · Critical

Score breakdown

Description

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.

Status

Package Ubuntu Release Status
ruby2.3 26.10 stonking Not in release
26.04 LTS resolute Not in release
25.10 questing Not in release
24.04 LTS noble Not in release
22.04 LTS jammy Not in release
16.04 LTS xenial
Fixed in 2.3.1-2~ubuntu16.04.16+esm15
ruby2.5 26.10 stonking Not in release
26.04 LTS resolute Not in release
25.10 questing Not in release
24.04 LTS noble Not in release
22.04 LTS jammy Not in release
18.04 LTS bionic
Needs evaluation
ruby2.7 26.10 stonking Not in release
26.04 LTS resolute Not in release
25.10 questing Not in release
24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Needs evaluation
ruby3.0 26.10 stonking Not in release
26.04 LTS resolute Not in release
25.10 questing Not in release
24.04 LTS noble Not in release
22.04 LTS jammy
Needs evaluation
ruby3.2 26.10 stonking Not in release
26.04 LTS resolute Not in release
25.10 questing Not in release
24.04 LTS noble
Needs evaluation
22.04 LTS jammy Not in release
ruby3.3 26.10 stonking
Needs evaluation
26.04 LTS resolute
Needs evaluation
25.10 questing Ignored end of life, was needs-triage
24.04 LTS noble Not in release
22.04 LTS jammy Not in release
jruby 26.10 stonking
Needs evaluation
26.04 LTS resolute
Not affected
25.10 questing Ignored end of life, was needs-triage
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial
Needs evaluation
14.04 LTS trusty
Not affected

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Severity score breakdown

CVSS version:

Base score 1.7 · Low

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

Base score 9.8 · Critical

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

Other references

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