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VulnerabilityPublished Updated

CVE-2026-32934: github.com/coredns/coredns · CoreDNS' DoQ worker pool does not bound stream backlog

Affects github.com/coredns/corednsSource GCVE Database

0

Mentioned vulnerabilities

Authoritative record:CVE-2026-32934· High 8.7

Not known to be exploited · CVSS 8.7 High : upgrade to 1.14.3 soon.

Data as of 27 Oct 2026, 00:07 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 1.14.3
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 5 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 26 Oct 2026.

What to do

Upgrade github.com/coredns/coredns to 1.14.3.

Affected software

ProductAffectedFixed in
Gogithub.com/coredns/corednsAffected
  • <1.14.3
Fixed in
  • 1.14.3

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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 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.

References

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