Cyber Resilience

CVE-2026-5950

Isc Bind 9.18.36 – 9.18.49

Published
20 May 2026
Modified
23 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 5.3
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:L
EPSS Score 0.0066 48th percentile
Risk Priority 45 floored blend · peak EPSS

Summary

CVE-2026-5950 is a medium-severity Unchecked Input for Loop Condition (CWE-606) vulnerability in Isc Bind. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 48th 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 SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions…

more

9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

CWE(s)
CWE-606

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability 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 →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-3119Same product: Isc Bind
CVE-2026-1519Same product: Isc Bind
CVE-2026-3104Same product: Isc Bind
CVE-2026-5946Same product: Isc Bind
CVE-2026-3592Same product: Isc Bind
CVE-2026-3039Same product: Isc Bind
CVE-2026-5947Same product: Isc Bind
CVE-2026-3591Same product: Isc Bind
CVE-2026-3593Same product: Isc Bind
CVE-2023-5517Same product: Isc Bind

Affected Assets

isc
bind
9.18.36 — 9.18.49 · 9.20.8 — 9.20.23 · 9.21.7 — 9.21.21

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V17.3.2
  • V4.3.1

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

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

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

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

A.8.25 Secure development life cycle partial match
prevents

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

A.8.26 Application security requirements partial match
prevents

Application security requirements include input validation rules that mitigate excessive looping from untrusted data.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly mandate validation of loop-control inputs to prevent unbounded iteration.

References