Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-50868 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Isc Bind. Its CVSS base score is 7.5 (High).
Operationally, ranked in the top 0.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SC-5 (Denial-of-service Protection) and SC-6 (Resource Availability) — 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.
The vulnerability is a denial-of-service condition in the Closest Encloser Proof mechanism defined by RFC 5155 for DNSSEC when the guidance in RFC 9276 is not applied. It affects DNS implementations that perform NSEC3 processing, where an attacker-supplied response can force repeated SHA-1 iterations, resulting in high CPU consumption. The issue is tracked as CWE-400 and carries a CVSS 3.1 score of 7.5 with network attack vector and high availability impact.
Remote unauthenticated attackers can exploit the flaw by sending specially crafted DNSSEC responses as part of a random subdomain attack, causing the target resolver or authoritative server to expend excessive CPU resources validating NSEC3 records. Because the specification permits thousands of hash iterations in certain cases, even modest query volumes can degrade service availability without requiring authentication or user interaction.
Advisories published by Red Hat, SUSE, and the oss-security mailing list reference the original IETF specification in RFC 5155 and note the availability of configuration or code changes that limit NSEC3 iteration counts.
EPSS for the CVE rose from low values to a peak of 0.4388 on 2025-12-11 before receding to the current 0.1211, indicating a clear increase in observed exploitation interest after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-55601
Vulnerability Data
The Closest Encloser Proof aspect of the DNS protocol (in RFC 5155 when RFC 9276 guidance is skipped) allows remote attackers to cause a denial of service (CPU consumption for SHA-1 computations) via DNSSEC responses in a random subdomain attack,…
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aka the "NSEC3" issue. The RFC 5155 specification implies that an algorithm must perform thousands of iterations of a hash function in certain situations.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SC-5 directly limits the effects of resource-exhaustion events that constitute uncontrolled consumption.
SC-6 enforces explicit allocation limits on resources, structurally preventing the weakness from occurring.
Process isolation confines resource consumption to separate domains, reducing blast radius without stopping the root flaw.
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.
Pre-agreed severity-based prioritization and resource allocation during incident triage reduce the likelihood that an attacker-induced resource exhaustion will overwhelm the organization before corrective action is taken.
Early notification of anomalous resource consumption or system malfunctions enables throttling or isolation before availability is lost.
Specifying log storage limits and rotation procedures reduces the risk that unbounded log growth will exhaust disk or memory resources and cause denial of service.
Resource-utilization monitoring and alerting on bottlenecks or overloads limits the impact of denial-of-service or resource-exhaustion attacks.
A.8.20 implements network-level protections (firewalls, segmentation, protocol hardening, monitoring, authentication of systems/devices) that can limit abuse of a resource-consuming weakness but do not stop the weakness from being exploitable; the flaw remains present in the product and can still be triggered from an authorized or internal context.
Monitoring network service usage and applying controls to restrict access when necessary limits an attacker’s ability to consume excessive resources through unrestricted or unauthenticated service calls.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-400, a class-level weakness. Rules are authored against its narrower children: CWE-770.