CoreDNS: Unauthenticated memory exhaustion in custom transports
### 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](https://github.com/coredns/coredns/blob/18a58b9e898ccd95c3f8ee72a37b95b3d1e3e928/plugin/pkg/doh/doh.go#L134-L155). DoH3 uses the same decoder. - [DoQ stream handling](https://github.com/coredns/coredns/blob/18a58b9e898ccd95c3f8ee72a37b95b3d1e3e928/core/dnsserver/server_quic.go#L212-L219). - [DNS-over-gRPC query handling](https://github.com/coredns/coredns/blob/18a58b9e898ccd95c3f8ee72a37b95b3d1e3e928/core/dnsserver/server_grpc.go#L176-L184). This differs from the [miekg/dns](https://github.com/miekg/dns) UDP and TCP server. Its [`serveDNS`](https://github.com/miekg/dns/blob/v1.1.72/server.go#L628-L643) path decodes the fixed 12-byte header and invokes [`DefaultMsgAcceptFunc`](https://github.com/miekg/dns/blob/v1.1.72/acceptfunc.go#L33-L57) 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 reque
GHSA-mrg3-qvqr-jw29
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:GHSA-mrg3-qvqr-jw29
github.com/coredns/coredns
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.14.7
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.14.7"
}
]
}
],
"package": {
"name": "github.com/coredns/coredns",
"purl": "pkg:golang/github.com/coredns/coredns",
"ecosystem": "Go"
},
"database_specific": {
"source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-mrg3-qvqr-jw29/GHSA-mrg3-qvqr-jw29.json",
"last_known_affected_version_range": "<= 1.14.6"
}
}
]- Related CVEs
- CVE-2026-82399
Source reference:
/aliases
Publisher severity
high
Source reference: /database_specific/severity
- Event
- #23406 · Revision 1
- Added to Heist Feed
- Publisher date