Cyber Resilience

CVE-2026-1519

DoS in Isc Bind 9.11.0 – 9.16.50

DoS
Published
25 March 2026
Modified
03 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.016 74th percentile
Risk Priority 61 floored blend · peak EPSS

Summary

CVE-2026-1519 is a high-severity Unchecked Input for Loop Condition (CWE-606) vulnerability in Isc Bind. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Network Denial of Service (T1498); ranked in the top 26% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-10 (Concurrent Session Control) 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.

CVE-2026-1519 is a denial-of-service vulnerability in BIND 9 resolvers that perform DNSSEC validation. When such a resolver processes a maliciously crafted DNS zone, it may consume excessive CPU resources, leading to degraded performance or service disruption. The issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1. Authoritative-only servers are generally unaffected, though they may be vulnerable in scenarios where they issue recursive queries.

Remote attackers can exploit this vulnerability over the network with low complexity and no required privileges or user interaction, as indicated by 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). By sending a specially crafted zone to a targeted BIND resolver performing DNSSEC validation, an attacker can trigger high CPU utilization, resulting in a denial-of-service condition that impacts availability without affecting confidentiality or integrity.

ISC has released patched versions including BIND 9.18.47, 9.20.21, and 9.21.20 to address the vulnerability; administrators should update affected installations promptly. Additional details are available in the ISC knowledge base article at https://kb.isc.org/docs/cve-2026-1519, which also references circumstances under which authoritative servers might make recursive queries and thus be exposed. Debian LTS users are advised via announcement at https://lists.debian.org/debian-lts-announce/2026/04/msg00008.html.

EU & UK References

Vulnerability Data

If a BIND resolver is performing DNSSEC validation and encounters a maliciously crafted zone, the resolver may consume excessive CPU. Authoritative-only servers are generally unaffected, although there are circumstances where authoritative servers may make recursive queries (see: https://kb.isc.org/docs/why-does-my-authoritative-server-make-recursive-queries). This issue…

more

affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1.

CWE(s)
CWE-606CWE-770

Related Threats

MITRE ATT&CK Enterprise Techniques

T1498 Network Denial of Service Impact
Adversaries may perform Network Denial of Service (DoS) attacks to degrade or block the availability of targeted resources to users.
attack.mitre.org →
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
T1499.003 Application Exhaustion Flood Impact
Adversaries may target resource intensive features of applications to cause a denial of service (DoS), denying availability to those applications.
attack.mitre.org →
T1498.001 Direct Network Flood Impact
Adversaries may attempt to cause a denial of service (DoS) by directly sending a high-volume of network traffic to a target.
attack.mitre.org →
T1498.002 Reflection Amplification Impact
Adversaries may attempt to cause a denial of service (DoS) by reflecting a high-volume of network traffic to a target.
attack.mitre.org →
T1499.001 OS Exhaustion Flood Impact
Adversaries may launch a denial of service (DoS) attack targeting an endpoint's operating system (OS).
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-3039Same product: Isc Bind
CVE-2026-5950Same product: Isc Bind
CVE-2026-3592Same product: Isc Bind
CVE-2026-3104Same product: Isc Bind
CVE-2026-3119Same product: Isc Bind
CVE-2026-5946Same product: Isc Bind
CVE-2026-3591Same product: Isc Bind
CVE-2026-3593Same product: Isc Bind
CVE-2026-5947Same product: Isc Bind
CVE-2023-6516Same product: Isc Bind

Affected Assets

isc
bind
9.11.0 — 9.16.50 · 9.18.0 — 9.18.47 · 9.20.0 — 9.20.21

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V17.3.2
  • V4.3.1
  • V15.4.4

Mitigating Controls (NIST 800-53 r5) AI

AC-10 Concurrent Session Control good match

Directly enforces a hard limit on concurrent sessions, structurally preventing unbounded resource allocation.

SC-6 Resource Availability good match

Requires explicit allocation of resources by priority or quota, directly stopping unlimited allocation.

SI-10 Information Input Validation good match

Input validation directly stops untrusted values from reaching loop conditions without bounds or sanity checks.

AC-7 Unsuccessful Logon Attempts partial match

Imposes a limit on consecutive invalid attempts, preventing one specific class of unbounded resource consumption.

SC-5 Denial-of-service Protection partial match

Reduces impact of resulting DoS events without preventing the underlying lack of allocation limits.

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.

PR.IR-04 mostly match
degrades

Monitoring capacity and taking action to maintain availability directly reduces unchecked resource allocation.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require input validation and bounds checking that prevent unchecked loop 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.

A.8.16 Monitoring activities mostly match
finds

Baseline comparison of CPU, memory and bandwidth usage helps surface uncontrolled resource allocations before they cause service degradation.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect and block unchecked loop conditions before release.

A.8.6 Capacity management mostly match
prevents

Capacity projections and elasticity measures ensure that allocation requests are bounded and can be throttled, reducing the window in which an attacker can force unbounded resource reservations.

A.8.13 Information backup partial match
mitigates

Defining retention periods and deletion schedules for backup copies prevents indefinite accumulation of data on storage media without corresponding resource-management controls.

A.8.14 Redundancy of information processing facilities partial match
mitigates

Architectural redundancy and automatic failover limit the impact of an attacker who forces excessive allocations, because spare capacity can absorb the load until the primary instance recovers.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle requires input validation and bounds checking that can prevent unchecked loop conditions.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248552 OL 8 must be configured so that all network connections associated with SSH traffic terminate after becoming unresponsive. prevents CWE-770
  • V-248553 OL 8 must be configured so that all network connections associated with SSH traffic are terminated after 10 minutes of becoming unresponsive. prevents CWE-770
Oracle Linux 9 (2 rules)
  • V-271710 OL 9 must be configured so that all network connections associated with SSH traffic are terminated after 10 minutes of becoming unresponsive. prevents CWE-770
  • V-271709 OL 9 must be configured so that all network connections associated with SSH traffic terminate after becoming unresponsive. prevents CWE-770
RHEL 8 (1 rule)
  • V-230244 RHEL 8 must be configured so that all network connections associated with SSH traffic terminate after becoming unresponsive. prevents CWE-770

References