Vulnerability in github.com/coredns/coredns (CVE-2026-82399)
Summary
Vulnerability in github.com/coredns/coredns (CVE-2026-82399). Risk of unauthorized operations or information disclosure. Exploitable via dns.Msg.Unpack. Mitigation: upgrade to 1.14.7 or later.
Original description
The description as published by the source.
Summary
CoreDNS parses attacker-controlled DNS section counts before validating them on DNS-over-HTTPS (DoH and DoH3), DNS-over-QUIC (DoQ), and DNS-over-gRPC listeners. An unauthenticated client can use DNS name compression to make one
65,533-byte request allocate more than 10 MiB while it is unpacked. Concurrent requests can exhaust memory and terminate CoreDNS.
Details
The affected request paths call dns.Msg.Unpack directly:
- DoH POST and GET decoding. DoH3 uses the same decoder.
- DoQ stream handling.
- DNS-over-gRPC query handling.
This differs from the miekg/dns UDP and TCP server. Its serveDNS path decodes the fixed 12-byte header and invokes DefaultMsgAcceptFunc before unpacking the DNS sections. The default policy rejects requests unless QDCOUNT is exactly one and also limits the other section counts. CoreDNS's custom transports bypass this early validation.
Parsing happens before the plugin chain. Plugin-level rate limiting or…
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-2026-82399 has been found in github.com/coredns/coredns.
Attackers can target a specific entry point like dns.Msg.Unpack over the network to misuse the product.
Risk of unauthorized operations or information disclosure. 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-2026-82399" on the vendor's site.
CVE-2026-82399 (github.com/coredns/coredns) — CWE-770 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: dns.Msg.Unpack / serveDNS / DefaultMsgAcceptFunc / QDCOUNT
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-770) exists in github.com/coredns/coredns. Attackers reach the vulnerable code path via dns.Msg.Unpack without authentication.
Check the vendor advisory for the affected versions of github.com/coredns/coredns. Attack surface: dns.Msg.Unpack / serveDNS / DefaultMsgAcceptFunc / QDCOUNT.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
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