REDHAT-BUG-2316321
First published: Thu Oct 03 2024(Updated: )
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.
| Affected Software | Affected Version | How to fix |
|---|---|---|
| libunbound | <=1.21.0 |
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Reference Links
- https://nlnetlabs.nl/downloads/unbound/CVE-2024-8508.txt
- https://access.redhat.com/errata/RHSA-2024:11232
- https://access.redhat.com/errata/RHSA-2024:11170
- https://access.redhat.com/errata/RHSA-2025:0140
- https://access.redhat.com/errata/RHSA-2025:0837
- https://access.redhat.com/errata/RHSA-2025:1120
- https://bugzilla.redhat.com/show_bug.cgi?id=2316321
Frequently Asked Questions
What is the severity of REDHAT-BUG-2316321?
The severity of REDHAT-BUG-2316321 is considered medium due to potential denial-of-service implications.
How do I fix REDHAT-BUG-2316321?
To fix REDHAT-BUG-2316321, update NLnet Labs Unbound to version 1.21.1 or later.
What versions are affected by REDHAT-BUG-2316321?
NLnet Labs Unbound versions up to and including 1.21.0 are affected by REDHAT-BUG-2316321.
What type of vulnerability is REDHAT-BUG-2316321?
REDHAT-BUG-2316321 is a denial-of-service vulnerability that can be exploited through malformed large RRsets.
Who is responsible for REDHAT-BUG-2316321?
NLnet Labs is responsible for the vulnerability identified as REDHAT-BUG-2316321 in their Unbound software.
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