CVE-2026-26018
Published: 06 March 2026
Summary
CVE-2026-26018 is a high-severity PRNG (CWE-337) vulnerability in Coredns.Io Coredns. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 7.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SC-5 (Denial-of-service Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-26018 is a denial-of-service vulnerability affecting CoreDNS, a DNS server that chains plugins, in versions prior to 1.14.2. The flaw resides in the loop detection plugin, where a predictable pseudo-random number generator (PRNG) is used to generate a secret query name. When combined with a fatal error handler that terminates the entire process, specially crafted DNS queries can trigger a crash of the DNS server.
Any unauthenticated attacker with network access to the CoreDNS instance can exploit this vulnerability with low attack complexity and no user interaction required, as reflected in its CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Exploitation leads to a high-impact denial of service by fully terminating the server process, disrupting DNS resolution services.
CoreDNS has patched this issue in version 1.14.2. Administrators should upgrade to this version or later to mitigate the vulnerability. Additional details are available in the CoreDNS release notes at https://github.com/coredns/coredns/releases/tag/v1.14.2 and the GitHub security advisory at https://github.com/coredns/coredns/security/advisories/GHSA-h75p-j8xm-m278.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-10043
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated crash of CoreDNS (public-facing DNS server) via crafted queries directly enables T1190 (Exploit Public-Facing Application) for initial access/impact and T1499.004 (Application or System Exploitation) to achieve denial of service.
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mitigates the vulnerability by requiring timely remediation through patching to CoreDNS version 1.14.2 or later, fixing the predictable PRNG and fatal error handler.
Implements denial-of-service protections such as rate limiting and query filtering to block specially crafted DNS queries that crash the CoreDNS loop detection plugin.
Ensures secure error handling that prevents fatal process termination when the loop detection plugin encounters crafted queries exploiting the predictable PRNG.