Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:NSummary
CVE-2026-26017 is a high-severity Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367) vulnerability in Coredns.Io Coredns. Its CVSS base score is 7.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 31th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-25 (Reference Monitor) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-26017 is a logical vulnerability in CoreDNS, a DNS server that chains plugins, affecting versions prior to 1.14.2. The issue stems from the default execution order of plugins, where security plugins such as acl are evaluated before the rewrite plugin. This creates a Time-of-Check Time-of-Use (TOCTOU) flaw, classified as CWE-367, that allows DNS access controls to be bypassed. The vulnerability carries a CVSS v3.1 base score of 7.7 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N).
Attackers with low privileges can exploit this vulnerability over the network with low attack complexity and no user interaction required. Successful exploitation enables a scoped impact with high confidentiality consequences, allowing unauthorized access to sensitive DNS data by circumventing access control mechanisms.
CoreDNS has patched this issue in version 1.14.2. Security practitioners should upgrade to this version or later. Additional mitigation 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-c9v3-4pv7-87pr.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-10042
Vulnerability Data
CoreDNS is a DNS server that chains plugins. Prior to version 1.14.2, a logical vulnerability in CoreDNS allows DNS access controls to be bypassed due to the default execution order of plugins. Security plugins such as acl are evaluated before…
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the rewrite plugin, resulting in a Time-of-Check Time-of-Use (TOCTOU) flaw. This issue has been patched in version 1.14.2.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V15.4.2V17.2.6
Mitigating Controls (NIST 800-53 r5) AI
A reference monitor that is always invoked and analyzable structurally eliminates the non-atomic check-then-use pattern underlying TOCTOU.
Access enforcement that performs an atomic check-and-use decision directly stops the window in which a TOCTOU race can be exploited.
Process isolation limits the blast radius of a successful TOCTOU exploitation but does not remove the race itself.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly include coding standards and reviews that prevent TOCTOU race conditions.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Reliable, synchronized time across systems narrows the exploitable window in which a resource state can change between a security check and its use.