GHSA-2wpx-qpw2-g5h5

Suggest an improvement
Source
https://github.com/advisories/GHSA-2wpx-qpw2-g5h5
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-2wpx-qpw2-g5h5/GHSA-2wpx-qpw2-g5h5.json
JSON Data
https://api.test.osv.dev/v1/vulns/GHSA-2wpx-qpw2-g5h5
Aliases
Downstream
CGA (44)
MINI (20)
Published
2026-04-28T22:40:38Z
Modified
2026-07-17T21:11:38Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
  • 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS Calculator
Summary
CoreDNS' DoQ worker pool does not bound stream backlog
Details

Summary

CoreDNS' DNS-over-QUIC (DoQ) server can be driven into large goroutine and memory growth by a remote client that opens many QUIC streams and stalls after sending only 1 byte. Even with a small configured quic { worker_pool_size ... }, CoreDNS still spawns a goroutine per accepted stream (workers + waiters) and active workers can block indefinitely in io.ReadFull() with no per-stream read deadline, enabling unauthenticated remote DoS via memory exhaustion/OOM-kill.

Details

CoreDNS' DoQ server uses a global worker pool (streamProcessPool) to limit concurrent stream processing, but when the pool is full it still spawns a goroutine per accepted stream that waits to acquire a worker token: select { case s.streamProcessPool <- ...: go ...; default: go ... wait for token ... } (core/dnsserver/server_quic.go)

Additionally, the DoQ message framing reads are blocking io.ReadFull() calls with no per-stream read deadline: readDOQMessage() reads the 2-byte length prefix and message body via io.ReadFull() (core/dnsserver/server_quic.go)

This allows an attacker to pin all workers by sending 1 byte (so io.ReadFull() blocks waiting for the second byte of the DoQ length prefix), while also creating an unbounded backlog of goroutines waiting for a worker token.

Note: this appears to be a result of an incomplete fix/regression for CVE-2025-47950 (GHSA-cvx7-x8pj-x2gw).

PoC

  1. Adjust COREDNS_BIN in the PoC to point at right path (see the top-level const definitions for tunables as well)
  2. Run python3 ./doq-dos-repro.py
  3. Expected sample output: *** Start CoreDNS *** Corefile: /tmp/vh-f003-doq-mem-regression/Corefile Log: /tmp/vh-f003-doq-mem-regression/coredns.log

*** Baseline sample (idle) *** rss_kib=49380 go_goroutines=17

*** Build + run partial-stream flooder *** go: downloading golang.org/x/net v0.43.0 go: downloading golang.org/x/crypto v0.41.0 go: downloading go.uber.org/mock v0.5.2 go: downloading github.com/stretchr/testify v1.11.1 go: downloading golang.org/x/sys v0.35.0 go: downloading github.com/pmezard/go-difflib v1.0.0 go: downloading github.com/davecgh/go-spew v1.1.1 go: downloading gopkg.in/yaml.v3 v3.0.1

*** Candidate sample (during attack) *** rss_kib=137968 go_goroutines=15557

*** Flooder output *** opened conns=60 streams_per_conn=256 total_streams=15360

*** Wrote results *** /tmp/vh-f003-doq-mem-regression/results.json

*** OK *** DoQ flood caused goroutine/RSS growth despite worker_pool_size.

Impact

Unauthenticated remote DoS on an encrypted DNS transport via goroutine/RSS growth leading to OOM-kill/crash and service outage.

Database specific 
{
    "cwe_ids": [
        "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-28T22:40:38Z",
    "nvd_published_at": "2026-05-05T20:16:35Z",
    "severity": "HIGH"
}
References

Affected packages

Go / github.com/coredns/coredns

Package

Name
github.com/coredns/coredns
View open source insights on deps.dev
Purl
pkg:golang/github.com/coredns/coredns

Affected ranges

Type
SEMVER
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1.14.3

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-2wpx-qpw2-g5h5/GHSA-2wpx-qpw2-g5h5.json"