CVE-2026-86003
MEDIUMDescription
CoreDNS is a DNS server written in Go. Prior to 1.14.7, the DNS-over-HTTPS, DNS-over-HTTP/3, DNS-over-QUIC, and DNS-over-gRPC listeners in plugin/pkg/doh/doh.go, core/dnsserver/server_quic.go, and core/dnsserver/server_grpc.go call dns.Msg.Unpack without the dns.DefaultMsgAcceptFunc request policy used by UDP, TCP, and DNS-over-TLS. An unauthenticated client can send an RFC 2136 UPDATE that the proxy or forward plugin passes unchanged to an update-capable upstream. If that upstream trusts CoreDNS's source address or connection and does not require an attacker-unknown end-to-end TSIG, the request appears to originate from CoreDNS and can add, replace, or delete DNS records, redirect traffic, take over names, alter mail routing, or disrupt the writable zone. This issue is fixed in version 1.14.7.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 37% of all known CVEs.
References
Related Vulnerabilities
Other CWE-441 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-47269 | High | 8.3 | 43% | - | - |
| CVE-2019-3924 | High | 7.5 | 16% | - | Fix |
| CVE-2020-5412 | Medium | 6.5 | 10% | - | Fix |
| CVE-2019-3996 | Medium | 6.5 | 5.9% | - | - |
| CVE-2026-83548 | Critical | 10.0 | 4.7% | KEV | Fix |
| CVE-2019-1841 | Medium | 6.5 | 2.6% | - | Fix |
Common questions
How do I fix CVE-2026-86003?
No published fix for CVE-2026-86003 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-86003 being actively exploited?
Not that we know of. CVE-2026-86003 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.44% is the estimated probability that it will be exploited in the next 30 days. That is higher than 37% of all scored CVEs.
How severe is CVE-2026-86003?
CVE-2026-86003 has a CVSS v3 base score of 5.9, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-17.