CVE-2026-27820

LOW EPSS 42.4%
Published Apr 16, 20262mo ago · Modified Jun 17, 20262w ago
1.7 CVSS 4.0
Low
Find Similar
Published Apr 16, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
1.7
Exploitability
—
Impact
—
Vector string
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
42.4% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 2

CWE-120
CWE-131

Affected Products 3

VendorProductVersionRange
ruby-langzlib* <3.0.1
ruby-langzlib*≥3.1.0  –  <3.1.2
ruby-langzlib*≥3.2.0  –  <3.2.3

References 2

  • github.com https://github.com/ruby/zlib/security/advisories/GHSA-g857-hhfv-j68w
    Vendor Advisory
  • hackerone.com https://hackerone.com/reports/3467067
    Permissions Required

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.