Withdrawn by the publisher.

Affected: CleanStart: kubernetes-dns-node-cache

Package kubernetes-dns-node-cache version 1.25.0-r8 fixes 17 vulnerabilities: CVE-2026-41178, CVE-2026-35579, CVE-2026-46600, CVE-2025-64702, CVE-2025-68151...

CoreDNS is a DNS server that chains plugins. Starting in version 1.2.0 and prior to version 1.12.4, the CoreDNS etcd plugin contains a TTL confusion vulnerability where lease IDs are incorrectly used as TTL values, enabling DNS cache pinning attacks. This effectively creates a DoS condition for DNS resolution of affected services. The `TTL()` function in `plugin/etcd/etcd.go` incorrectly casts etcd lease IDs (64-bit integers) to uint32 and uses them as TTL values. Large lease IDs become very large TTLs when cast to uint32. This enables cache pinning attacks. Version 1.12.4 contains a fix for the issue.

Affected: Go: github.com/coredns/coredns

# Summary

The CoreDNS etcd plugin contains a TTL confusion vulnerability where lease IDs are incorrectly used as TTL values, enabling cache pinning for very long periods. This can effectively cause a denial of service for DNS updates/changes to affected services.

# Details

In `plugin/etcd/etcd.go`, the `TTL()` function casts the 64-bit etcd lease ID to a uint32 and uses it as the TTL:

```go func (e *Etcd) TTL(kv *mvccpb.KeyValue, serv *msg.Service) uint32 { etcdTTL := uint32(kv.Lease) // BUG: Lease ID != TTL duration // ... rest of function uses etcdTTL as actual TTL } ```

Lease IDs are identifiers, not durations. Large lease IDs can produce very large TTLs after truncation, causing downstream resolvers and clients to cache answers for years.

This enables cache pinning attacks, such as:

1. Attacker has etcd write access (compromised service account, misconfigured RBAC/TLS, exposed etcd, insider). 2. Attacker writes/updates a key and attaches any lease (the actual lease duration is irrelevant; the ID is misused). 4. CoreDNS serves the record with an extreme TTL; downstream resolvers/clients cache it for a very long time. 5. Even after fixing/deleting the key (or restarting CoreDNS), clients continue to use the cached answer until their caches expire or enforce their own TTL caps.

Some resolvers implement TTL caps, but values and defaults vary widely and are not guaranteed.

# PoC

1. Launch etcd:

```bash etcd \ --data-dir ./etcd-data \ --listen-client-ur…

Affected: openEuler:20.03-LTS-SP4: coredns, openEuler:22.03-LTS-SP4: coredns, openEuler:24.03-LTS-SP1: coredns, openEuler:24.03-LTS-SP3: coredns

CoreDNS is a fast and flexible DNS server. The key word here is flexible: with CoreDNS you are able to do what you want with your DNS data by utilizing plugins. Security Fix(es):

CoreDNS is a DNS server that chains plugins. Starting in version 1.2.0 and prior to version 1.12.4, the CoreDNS etcd plugin contains a TTL confusion vulnerability where lease IDs are incorrectly used as TTL values, enabling DNS cache pinning attacks. This effectively creates a DoS condition for DNS resolution of affected services. The `TTL()` function in `plugin/etcd/etcd.go` incorrectly casts etcd lease IDs (64-bit integers) to uint32 and uses them as TTL values. Large lease IDs become very large TTLs when cast to uint32. This enables cache pinning attacks. Version 1.12.4 contains a fix for the issue.(CVE-2025-58063)

coredns-1.12.4-2.1 on GA media

Ein entfernter, authentisierter Angreifer kann eine Schwachstelle in CoreDNS ausnutzen, um einen Denial of Service Angriff durchzuführen.