CVE-2024-1931
Published: 07 March 2024
Summary
CVE-2024-1931 is a high-severity Infinite Loop (CWE-835) vulnerability in Fedoraproject Fedora. Its CVSS base score is 7.5 (High).
Operationally, ranked in the top 8.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Deeper analysis
NLnet Labs Unbound versions 1.18.0 through 1.19.1 contain an infinite-loop flaw (CWE-835) that produces a denial of service. The defect was introduced when support for Extended DNS Error (EDE) records was added; before stripping EDE records that exceed a client’s advertised UDP buffer size, the code attempts to trim the accompanying text fields while preserving the EDE codes. An unchecked condition in this trimming routine causes unbounded looping when Unbound generates a positive response containing EDE information and the client buffer is smaller than required. The issue is reachable only when the non-default “ede: yes” configuration option is enabled.
An unauthenticated remote attacker can trigger the loop by sending a query that elicits such a response, resulting in a persistent denial of service (CVSS 7.5). Because the vulnerable code path lies in Unbound’s reply-generation logic, exploitation requires only network reachability to a configured resolver and does not depend on crafted DNSSEC material or other special query features.
Upstream corrected the flaw in Unbound 1.19.2. Distribution advisories for Fedora and FreeBSD, together with NetApp’s security bulletin, recommend upgrading to the patched release or disabling the ede option as immediate mitigations. The EPSS score has remained flat at 0.0675 with no observed increase after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-17653
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.