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

What is CVE-2024-8508?

CVE-2024-8508 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 3 Oct 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-1284, CWE-606

Which versions are affected by CVE-2024-8508?

3 open source packages ship an affected version, including hickory-proto. It affects 2 products.

Products include Debian Debian Linux, Nlnetlabs Unbound.

How do I fix CVE-2024-8508?

Upgrade hickory-proto to 0.26.1 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2024-8508 being exploited?

There is no known exploitation of CVE-2024-8508 in the wild and no public exploit code.

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All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2024-8508, ALSA-2024:11232, ALSA-2025:8047, AZL-49915, AZL-49976, CLSA-2025-1736503760 and 32 more.