Vulnerability in github.com/coredns/coredns (CVE-2026-86003)
Summary
Vulnerability in github.com/coredns/coredns (CVE-2026-86003). Data can be tampered with by attackers. Exploitable via proxy. Mitigation: upgrade to 1.14.7 or later.
Original description
The description as published by the source.
Summary
CoreDNS accepted RFC 2136 UPDATE messages over DoH, DoH3, DoQ, and DNS-over-gRPC, then allowed the proxy/forward plugin to send them unchanged to an upstream DNS server. UDP, TCP, and DoT rejected the same opcode before plugin dispatch.
If an update-capable upstream trusts CoreDNS's source address or authenticated connection instead of requiring end-to-end TSIG, an unauthenticated client can use CoreDNS to add, replace, or delete DNS records.
Details
The affected listeners called dns.Msg.Unpack without the request policy used by the UDP/TCP server:
CoreDNS routed the message using its Zone question without checking the opcode. forward then passed the original message to the upstream.
By contrast, [dns.DefaultMsgAcceptFunc](https://github.com/miekg/dns/blob/v1.1.72/…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-86003 has been found in github.com/coredns/coredns.
Attackers can target a specific entry point like proxy over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.5/10.
What to do: upgrade github.com/coredns/coredns to 1.14.7 or later.
If unsure, ask your IT team or search "github.com/coredns/coredns CVE-2026-86003" on the vendor's site.
CVE-2026-86003 (github.com/coredns/coredns) — CWE-441 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: proxy / forward / dns.Msg.Unpack / dns.DefaultMsgAcceptFunc
Patched: 1.14.7 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-441) exists in github.com/coredns/coredns. Attackers reach the vulnerable code path via proxy without authentication.
Check the vendor advisory for the affected versions of github.com/coredns/coredns. Attack surface: proxy / forward / dns.Msg.Unpack / dns.DefaultMsgAcceptFunc.
Severity: High (CVSS 7.5/10). Data can be tampered with by attackers.
Update to 1.14.7.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/coredns/coredns' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/coredns/coredns' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/coredns/corednsを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/coredns/coredns to 1.14.7ステージング環境で 1.14.7 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- web github.com
- web github.com
- web github.com
- web nvd.nist.gov
- web github.com