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

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.

Published: 2024-10-03 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-8508 is rated Low Risk (39.9/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.81%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2024-8508

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.23% 0.81% +0.58%
2 2025-11-21 0.85% 0.23% -0.62%
3 2025-11-18 — 0.85% —

Full EPSS history (31 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-8508

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2024-8508

OS Trackers for CVE-2024-8508

vendor priority summary link
alpine — CVE-2024-8508: 1 source package rows (unbound); 51 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 9, open 42. https://security.alpinelinux.org/vuln/CVE-2024-8508
debian not yet assigned CVE-2024-8508 not yet assigned priority: Debian including 1 source packages (unbound), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2024-8508
redhat medium — https://access.redhat.com/security/cve/CVE-2024-8508
suse medium CVE-2024-8508 severity moderate: SUSE including 39 source package names (libssh-config-0.10.6-slfo.1.1_2.1, libssh4-0.10.6-slfo.1.1_2.1, …), 104 product×package rows across 39 product lines (Image SL-Micro, Image SL-Micro-Base, … (39 product lines)): Fixed 104. https://www.suse.com/security/cve/CVE-2024-8508/
ubuntu medium CVE-2024-8508 medium priority: Ubuntu including 1 source packages (unbound), 8 status rows across 8 suites (bionic, focal, jammy, noble, oracular, trusty, upstream, xenial): released 8. https://ubuntu.com/security/CVE-2024-8508

Affected software / configurations for CVE-2024-8508

Vendor Product Version Raw CPE
nlnetlabs unbound < 1.21.1 cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2024-8508

cvelogic Threat Intelligence