Improper Handling of Length Parameter Inconsistency Affecting resolv package, versions <0.3.2>=0.4.0, <0.7.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-RUBY-RESOLV-19477215
- published1 Sept 2026
- disclosed29 Aug 2026
- creditUnknown
Introduced: 29 Aug 2026
NewCVE-2026-80213 (opens in a new tab)How to fix?
Upgrade resolv to version 0.3.2, 0.7.2 or higher.
Overview
resolv is a Thread-aware DNS resolver library in Ruby.
Affected versions of this package are vulnerable to Improper Handling of Length Parameter Inconsistency via Resolv::DNS::MessageEncoder#put_string, put_label, and Resolv::DNS::Name.create in lib/resolv.rb. An attacker can make an application send a DNS query for the wrong hostname by supplying an overlong label or hostname to be encoded. put_string wrote the label length into a single octet without checking the range, so labels longer than 255 octets wrapped modulo 256 while the label bytes were still written unchanged. That lets attacker-controlled input produce wire bytes that decode to a different domain name than the one the application intended to resolve, which can bypass hostname allowlists and send lookups to an attacker-chosen name.