CVE-2024-1931: Denial of service when trimming EDE text on positive replies
First published: Thu Mar 07 2024(Updated: )
NLnet Labs Unbound version 1.18.0 up to and including version 1.19.1 contain a vulnerability that can cause denial of service by a certain code path that can lead to an infinite loop. Unbound 1.18.0 introduced a feature that removes EDE records from responses with size higher than the client's advertised buffer size. Before removing all the EDE records however, it would try to see if trimming the extra text fields on those records would result in an acceptable size while still retaining the EDE codes. Due to an unchecked condition, the code that trims the text of the EDE records could loop indefinitely. This happens when Unbound would reply with attached EDE information on a positive reply and the client's buffer size is smaller than the needed space to include EDE records. The vulnerability can only be triggered when the 'ede: yes' option is used; non default configuration. From version 1.19.2 on, the code is fixed to avoid looping indefinitely.
Credit: sep@nlnetlabs.nl
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Unbound | >=1.18.0<1.19.2 | |
| Red Hat Fedora | =38 | |
| Red Hat Fedora | =39 | |
| Red Hat Fedora | =40 |
Remedy
This issue is fixed in 1.19.2 and all later versions. For the vulnerable versions 1.18.0 up to and including 1.19.1, the option 'ede: no' (default configuration) is also a solution as it does not exercise the vulnerable code path.
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Reference Links
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2024-1931.txt
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4VCBRQ7KMSIGBQ6A4SBL5PF326DIJIIV/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/B2JUIFPA7H75Q2W3VXW2TUNHK6NVGOX4/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RBR4H7RCVMJ6H76S4LLRSY5EBFTYWGXK/
- https://lists.freebsd.org/archives/freebsd-security/2024-July/000283.html
- https://security.netapp.com/advisory/ntap-20240705-0006/
Frequently Asked Questions
What is the severity of CVE-2024-1931?
CVE-2024-1931 has a severity rating that indicates it can lead to denial of service due to an infinite loop in the affected versions.
Which versions are affected by CVE-2024-1931?
CVE-2024-1931 affects NLnet Labs Unbound version 1.18.0 through 1.19.1 inclusive.
How do I fix CVE-2024-1931?
To fix CVE-2024-1931, upgrade Unbound to version 1.19.2 or later.
What is the impact of CVE-2024-1931 on my system?
The impact of CVE-2024-1931 on your system includes potential denial of service, causing the service to become unresponsive.
Is CVE-2024-1931 specific to a certain operating system?
CVE-2024-1931 specifically affects various versions of the Fedora operating system in addition to other installations of Unbound.
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- vendor/nlnetlabs
- canonical/unbound
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- version/red hat fedora/40