CVE-2026-26018 CoreDNS Loop Detection Denial of Service Vulnerability
An attacker can crash the CoreDNS server by sending crafted queries that exploit predictable PRNGs in the loop detection plugin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-26018?
CVE-2026-26018 is a high-severity denial of service vulnerability in coredns, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
CoreDNS is a DNS server that chains plugins. Prior to version 1.14.2, a denial of service vulnerability exists in CoreDNS's loop detection plugin that allows an attacker to crash the DNS server by sending specially crafted DNS queries. The vulnerability stems from the use of a predictable pseudo-random number generator (PRNG) for generating a secret query name, combined with a fatal error handler that terminates the entire process. This issue has been patched in version 1.14.2.
Which versions are affected by CVE-2026-26018?
3 open source packages ship an affected version, including github.com/coredns/coredns. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/coredns/coredns Go | All versions | 1.14.2 |
github.com/coredns/coredns Go | All versions | 1.14.2 |
github.com/coredns/coredns Go | All versions | 1.14.2 |
Products include Coredns.io Coredns.
How do I fix CVE-2026-26018?
Upgrade github.com/coredns/coredns to 1.14.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-26018 being exploited?
There is no known exploitation of CVE-2026-26018 in the wild and no public exploit code.
Other vulnerabilities in coredns
- CVE-2026-32934 CoreDNS DNS-over-QUIC unbounded goroutine growth leads to denial of service
- CVE-2026-32936 CoreDNS DoH GET path missing size validation causes CPU and memory amplification
- CVE-2026-33190 CoreDNS TSIG authentication bypass on encrypted DNS transports
- CVE-2026-33489 CoreDNS transfer plugin subzone ACL bypass via lexicographic zone comparison
- CVE-2026-35579 CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports
Sources
Also known as AZL-79500, AZL-79529, CLEANSTART-2026-KF12369, CLEANSTART-2026-KZ65152, ECHO-9c6a-4edd-caa0, GHSA-h75p-j8xm-m278 and 22 more.