Cyber Resilience

CVE-2024-8508

Nlnetlabs Unbound ≤ 1.21.1

Published
03 October 2024
Modified
17 December 2024
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 0.0080 53th percentile
Risk Priority 46 floored blend · peak EPSS

Summary

CVE-2024-8508 is a medium-severity Unchecked Input for Loop Condition (CWE-606) vulnerability in Nlnetlabs Unbound. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 47% of CVEs by exploit likelihood; 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

NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very large RRsets can cause Unbound to spend a…

more

considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression calculations it is willing to do per packet. Packets that need more compression will result in semi-compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long. This change should not affect normal DNS traffic.

CWE(s)
CWE-606CWE-1284

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
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 →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-32665Same product: Nlnetlabs Unbound
CVE-2026-42534Same product: Nlnetlabs Unbound
CVE-2026-55991Same product: Nlnetlabs Unbound
CVE-2026-50046Same product: Nlnetlabs Unbound
CVE-2026-33278Same product: Nlnetlabs Unbound
CVE-2026-44687Same product: Nlnetlabs Unbound
CVE-2026-52863Same product: Nlnetlabs Unbound
CVE-2026-32792Same product: Nlnetlabs Unbound
CVE-2026-42955Same product: Nlnetlabs Unbound
CVE-2026-40691Same product: Nlnetlabs Unbound

Affected Assets

nlnetlabs
unbound
≤ 1.21.1
debian
debian linux
11.0

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)
  • V6.7.2
  • V17.3.2
  • V1.4.2
  • V2.1.1

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.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles encourage robust input handling but do not specifically address quantity validation.

A.8.28 Secure coding partial match
prevents

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

References