GHSA-2wpx-qpw2-g5h5
HIGHGHSA-2wpx-qpw2-g5h5 is a high-severity (CVSS 7.5) vulnerability in github.com/coredns/coredns. O3 Security confirms whether GHSA-2wpx-qpw2-g5h5 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
CoreDNS' DoQ worker pool does not bound stream backlog
Blast Radius
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Description
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
- Adjust COREDNS_BIN in the PoC to point at right path (see the top-level const definitions for tunables as well)
- Run python3 ./doq-dos-repro.py
- 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/coredns/coredns | all versions | 1.14.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/coredns/coredns. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/coredns/coredns to 1.14.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2wpx-qpw2-g5h5 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2wpx-qpw2-g5h5 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2wpx-qpw2-g5h5. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2wpx-qpw2-g5h5 in your dependencies?
O3 detects GHSA-2wpx-qpw2-g5h5 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.