Bug 2466863 (CVE-2026-32934)

Summary: CVE-2026-32934 coredns: github.com/coredns/coredns: CoreDNS: Denial of Service due to unbounded resource growth in DNS-over-QUIC (DoQ) stream handling
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: alcohan, gparvin, jbalunas, pahickey, rhaigner
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in CoreDNS, a DNS server that chains plugins. The DNS-over-QUIC (DoQ) server is vulnerable to unbounded resource growth. An unauthenticated remote attacker can exploit this by opening numerous QUIC streams and sending only one byte per stream, causing the server to spawn excessive goroutines and consume unbounded memory. This leads to memory exhaustion and a Denial of Service (DoS) condition, making the server unresponsive.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-05-05 20:01:58 UTC 
CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the DNS-over-QUIC (DoQ) server can be driven into unbounded goroutine and memory growth by a remote client that opens many QUIC streams and sends only 1 byte per stream. When the worker pool is full, CoreDNS still spawns a goroutine per accepted stream to wait for a worker token. Additionally, active workers block indefinitely in io.ReadFull() with no per-stream read deadline, allowing an attacker to pin all workers by sending a single byte so the read blocks waiting for the second byte of the DoQ length prefix. This enables an unauthenticated remote attacker to cause memory exhaustion and OOM-kill. This issue has been fixed in version 1.14.3. No known workarounds exist.