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NVD / CVE Program· CNA NLnet Labs

CVE-2024-8508: Unbounded name compression could lead to Denial of Service

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.80% (FIRST EPSS); higher than 56.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: azl3 unbound 1.19.1-4 on Azure Linux 3.0 1.19.1-4; cbl2 unbound 1.19.1-3 on CBL Mariner 2.0 1.19.1-3; cbl2 unbound 1.19.1-3 on CBL-Mariner 2.0 1.19.1-3.

Low priority for now. Upgrade to azl3 unbound 1.19.1-4 on Azure Linux 3.0 1.19.1-4; cbl2 unbound 1.19.1-3 on CBL Mariner 2.0 1.19.1-3; cbl2 unbound 1.19.1-3 on CBL-Mariner 2.0 1.19.1-3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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 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.

MediumCVSS 5.3 · v3.1—No exploit Fix available
Published
Oct 3, 2024
Updated
Jun 17, 2026
EPSS
0.8% · 56th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.3
CNA · NLnet Labs
5.3
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2024-8508

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
nlnetlabsunbound
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux11.0
  • nlnetlabs unboundbefore 1.21.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (NLnet Labs). Independent of NVD's CPE analysis and usually ahead of it.

  • NLnet Labs Unbound

    • up to and including 1.21.0affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10python3-unboundbefore 1.20.0-10.el10_01.20.0-10.el10_0
AlmaLinux:10unboundbefore 1.20.0-10.el10_01.20.0-10.el10_0
AlmaLinux:10unbound-anchorbefore 1.20.0-10.el10_01.20.0-10.el10_0
AlmaLinux:10unbound-develbefore 1.20.0-10.el10_01.20.0-10.el10_0
AlmaLinux:10unbound-dracutbefore 1.20.0-10.el10_01.20.0-10.el10_0
AlmaLinux:10unbound-libsbefore 1.20.0-10.el10_01.20.0-10.el10_0
AlmaLinux:8python3-unboundbefore 1.16.2-5.8.el8_101.16.2-5.8.el8_10
AlmaLinux:8unboundbefore 1.16.2-5.8.el8_101.16.2-5.8.el8_10
AlmaLinux:8unbound-develbefore 1.16.2-5.8.el8_101.16.2-5.8.el8_10
AlmaLinux:8unbound-libsbefore 1.16.2-5.8.el8_101.16.2-5.8.el8_10
AlmaLinux:9python3-unboundbefore 1.16.2-8.el9_5.11.16.2-8.el9_5.1
AlmaLinux:9unboundbefore 1.16.2-8.el9_5.11.16.2-8.el9_5.1
AlmaLinux:9unbound-develbefore 1.16.2-8.el9_5.11.16.2-8.el9_5.1
AlmaLinux:9unbound-libsbefore 1.16.2-8.el9_5.11.16.2-8.el9_5.1
Alpine:v3.17unboundbefore 1.20.0-r11.20.0-r1
Alpine:v3.21unboundbefore 1.21.1-r01.21.1-r0
crates.iohickory-protofrom 0.3.1 · before 0.26.10.26.1
Debian:11unboundbefore 1.13.1-1+deb11u41.13.1-1+deb11u4
Debian:12unboundbefore 1.17.1-2+deb12u31.17.1-2+deb12u3
Debian:13unboundbefore 1.21.1-11.21.1-1
openSUSE:Leap 15.5unboundbefore 1.20.0-150100.10.19.11.20.0-150100.10.19.1
openSUSE:Leap 15.6unboundbefore 1.20.0-150600.23.9.11.20.0-150600.23.9.1
openSUSE:Tumbleweedunboundbefore 1.21.1-1.11.21.1-1.1
Red Hat:enterprise_linux:10.0python3-unboundbefore 0:1.20.0-10.el10_00:1.20.0-10.el10_0

+52

Same product

nlnetlabs: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-25042Unbound before 1.9.5 allows an out-of-bounds write via a compressed name in rdata_copy.
    40Plan
  • CVE-2019-25039Unbound before 1.9.5 allows an integer overflow in a size calculation in respip/respip.c.
    40Plan
  • CVE-2019-25038Unbound before 1.9.5 allows an integer overflow in a size calculation in dnscrypt/dnscrypt.c.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2022-3204Sep 26, 2022 · A vulnerability named 'Non-Responsive Delegation Attack' (NRDelegation Attack) has been discovered in various DNS resolving software.
    30Monitor
  • ← EarlierCVE-2024-1931Mar 7, 2024 · Denial of service when trimming EDE text on positive replies
    31Monitor
  • Later →CVE-2026-32792May 20, 2026 · Packet of death with DNSCrypt
    18Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
azl3 unbound 1.19.1-4 on Azure Linux 3.01.19.1-4 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 unbound 1.19.1-3 on CBL Mariner 2.01.19.1-3 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 unbound 1.19.1-3 on CBL-Mariner 2.01.19.1-3 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:python3-unbound1.16.2-8.el9_5.1 · AlmaLinux:9Package registry (OSV)
almalinux:unbound1.16.2-8.el9_5.1 · AlmaLinux:9Package registry (OSV)
almalinux:unbound-anchor1.20.0-10.el10_0 · AlmaLinux:10Package registry (OSV)
almalinux:unbound-devel1.16.2-8.el9_5.1 · AlmaLinux:9Package registry (OSV)
almalinux:unbound-dracut1.20.0-10.el10_0 · AlmaLinux:10Package registry (OSV)
almalinux:unbound-libs1.16.2-8.el9_5.1 · AlmaLinux:9Package registry (OSV)
alpine:unbound1.20.0-r1 · Alpine:v3.17Package registry (OSV)
crates.io:hickory-proto0.26.1Package registry (OSV)
debian:unbound1.17.1-2+deb12u3 · Debian:12Package registry (OSV)
opensuse:unbound1.20.0-150100.10.19.1 · openSUSE:Leap 15.5Package registry (OSV)
red hat:python3-unbound0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::appstreamPackage registry (OSV)
red hat:python3-unbound-debuginfo0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::appstreamPackage registry (OSV)
red hat:unbound0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::appstreamPackage registry (OSV)
red hat:unbound-anchor0:1.20.0-10.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:unbound-anchor-debuginfo0:1.20.0-10.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:unbound-debuginfo0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::appstreamPackage registry (OSV)
red hat:unbound-debugsource0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::appstreamPackage registry (OSV)
red hat:unbound-devel0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::crbPackage registry (OSV)
red hat:unbound-dracut0:1.20.0-10.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:unbound-libs0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::appstreamPackage registry (OSV)
red hat:unbound-libs-debuginfo0:1.16.2-8.el9_4.1 · Red Hat:rhel_eus:9.4::appstreamPackage registry (OSV)
red hat:unbound-utils-debuginfo0:1.20.0-10.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
rocky linux:unbound0:1.16.2-8.el9_5.1 · Rocky Linux:9Package registry (OSV)
suse:unbound1.20.0-150100.10.19.1 · SUSE:Linux Enterprise Micro 5.5Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
low · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
Low

Weakness class (CWE)

CWE-606 · Unchecked Input for Loop Condition

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records