SB2026082726 - Multiple vulnerabilities in Ruby resolv gem

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Main Vulnerability Database SB2026082726

SB2026082726 - Multiple vulnerabilities in Ruby resolv gem

Published: August 27, 2026

Security Bulletin ID SB2026082726
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 2
Exploitation vector Remote access
Highest impact Denial of service

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 2 vulnerabilities.


1) Resource exhaustion (CVE-ID: CVE-2026-80212)

CWE-ID: CWE-400 - Resource exhaustion

CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to uncontrolled resource consumption in the resolv DNS resolution logic when processing malicious DNS responses from an attacker-controlled name server. A remote attacker can return crafted DNS responses that are retained permanently to cause a denial of service.

Only applications that resolve hostnames an attacker can influence through this gem are affected.


2) Input validation error (CVE-ID: CVE-2026-80213)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to bypass hostname validation restrictions.

The vulnerability exists due to improper input validation in the resolv hostname resolution logic when resolving a hostname after it has been checked against an allow list or SSRF filter. A remote attacker can supply a crafted hostname so that the validated string and the name sent to the network differ to bypass hostname validation restrictions.

This requires a hostname that exceeds DNS length limits.


Remediation

Install update from vendor's website.

References