SB2026042132 - Buffer overflow in Ruby Zlib gem
Published: April 21, 2026 Updated: April 21, 2026
Security Bulletin ID
SB2026042132
CSH Severity
High
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Buffer overflow (CVE-ID: CVE-2026-27820)
CWE-ID: CWE-120 - Buffer overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:U/U:Amber
The vulnerability allows a remote attacker to cause memory corruption.
The vulnerability exists due to buffer overflow in zstream_buffer_ungets() function when parsing input within the Zlib::GzipReader. A remote attacker can provide crafted input that causes the buffer length to exceed its capacity to cause memory corruption.
User interaction is required.
Remediation
Install update from vendor's website.