{"schema_version":"1.7.5","id":"GHSA-2wpx-qpw2-g5h5","published":"2026-04-28T22:40:38Z","modified":"2026-05-20T19:41:12.845480794Z","aliases":["CVE-2026-32934","GO-2026-4969"],"related":["CGA-cj8w-hr6g-6wvx"],"summary":"CoreDNS' DoQ worker pool does not bound stream backlog","details":"### Summary\nCoreDNS' 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.\n\n### Details\nCoreDNS' 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)\n\nAdditionally, 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)\n\nThis 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.\n\nNote: this appears to be a result of an incomplete fix/regression for CVE-2025-47950 (GHSA-cvx7-x8pj-x2gw).\n\n### PoC\n1. Adjust COREDNS_BIN in the PoC to point at right path (see the top-level const definitions for tunables as well)\n2. Run python3 ./doq-dos-repro.py\n3. Expected sample output:\n*** Start CoreDNS ***\nCorefile: /tmp/vh-f003-doq-mem-regression/Corefile\nLog: /tmp/vh-f003-doq-mem-regression/coredns.log\n\n*** Baseline sample (idle) ***\nrss_kib=49380 go_goroutines=17\n\n*** Build + run partial-stream flooder ***\ngo: downloading golang.org/x/net v0.43.0\ngo: downloading golang.org/x/crypto v0.41.0\ngo: downloading go.uber.org/mock v0.5.2\ngo: downloading github.com/stretchr/testify v1.11.1\ngo: downloading golang.org/x/sys v0.35.0\ngo: downloading github.com/pmezard/go-difflib v1.0.0\ngo: downloading github.com/davecgh/go-spew v1.1.1\ngo: downloading gopkg.in/yaml.v3 v3.0.1\n\n*** Candidate sample (during attack) ***\nrss_kib=137968 go_goroutines=15557\n\n*** Flooder output ***\nopened conns=60 streams_per_conn=256 total_streams=15360\n\n*** Wrote results ***\n/tmp/vh-f003-doq-mem-regression/results.json\n\n*** OK ***\nDoQ flood caused goroutine/RSS growth despite worker_pool_size.\n\n\n### Impact\nUnauthenticated remote DoS on an encrypted DNS transport via goroutine/RSS growth leading to OOM-kill/crash and service outage.","affected":[{"package":{"name":"github.com/coredns/coredns","ecosystem":"Go","purl":"pkg:golang/github.com/coredns/coredns"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"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"}}],"references":[{"type":"WEB","url":"https://github.com/coredns/coredns/security/advisories/GHSA-2wpx-qpw2-g5h5"},{"type":"WEB","url":"https://github.com/coredns/coredns/security/advisories/GHSA-cvx7-x8pj-x2gw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32934"},{"type":"PACKAGE","url":"https://github.com/coredns/coredns"},{"type":"WEB","url":"https://github.com/coredns/coredns/releases/tag/v1.14.3"}],"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"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V4","score":"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"}]}