VulnerabilityPublished 17 Sep 2026

CVE-2026-86003: github.com/coredns/coredns · CoreDNS DoH/DoQ/gRPC bypass UPDATE rejection enforced on UDP/TCP

Affects github.com/coredns/corednsSource GCVE Database

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Not known to be exploited · CVSS 7.5 High : upgrade to 1.14.7 soon.

Data as of 1 Nov 2026, 11:03 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.14.7

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade github.com/coredns/coredns to 1.14.7.

Affected software

Product	Affected	Fixed in
Gogithub.com/coredns/coredns	Affected <1.14.7	Fixed in 1.14.7

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and should be applied to CoreDNS to enforce the correct request acceptance policy on all affected transports (DoH, DoH3, DoQ, DNS-over-gRPC) before dispatching requests. This fix prevents UPDATE opcode messages from being forwarded unless properly authenticated. Users should upgrade to CoreDNS version 1.14.7 or later. No additional mitigation is required if the patch is applied.

Description

CoreDNS versions prior to 1.14.7 improperly accepted DNS UPDATE messages over DoH, DoH3, DoQ, and DNS-over-gRPC transports, allowing unauthenticated clients to send DNS UPDATE requests through the proxy/forward plugin to upstream DNS servers. This bypassed the opcode rejection enforced on UDP and TCP transports, potentially enabling unauthorized DNS record modifications if the upstream trusts CoreDNS's source or connection without end-to-end TSIG authentication. A fix is available that enforces the correct request policy on all affected transports before dispatch.

Impact

An unauthenticated attacker can send DNS UPDATE requests over DoH, DoH3, DoQ, or DNS-over-gRPC to a vulnerable CoreDNS server and cause it to forward these requests to an upstream DNS server. If the upstream server trusts CoreDNS's connection or source address without requiring end-to-end TSIG authentication, this can lead to unauthorized modification of DNS records (additions, replacements, deletions). This could compromise DNS integrity and potentially disrupt services relying on DNS.

CWE-441Unintended Proxy or Intermediary (Confused Deputy) (opens in a new tab)
Class weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere.
Architecture and Design
Enforce the use of strong mutual authentication mechanism between the two parties.
Architecture and Design
Whenever a product is an intermediary or proxy for transactions between two other components, the proxy core should not drop the identity of the initiator of the transaction. The immutability of the identity of the initiator must be maintained and should be forwarded all the way to the target.
OWASP Cheat Sheets
Authorization (opens in a new tab)
Attack patterns
XML Routing Detour Attacks (opens in a new tab)
Transparent Proxy Abuse (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 Sep 2026, 01:26 UTC

WeaknessesCWE-441

Technical details

References

Community reviews

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