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

> Attackers can poison the DNS cache by injecting forged records due to lenient validation of unsolicited answers in BIND.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Oct 2025
- **Updated:** 26 Feb 2026
- **Also known as:** ALPINE-CVE-2025-40778, ALSA-2025:19835, AZL-68727, AZL-68736, BELL-CVE-2025-40778, CLSA-2025-1764321323, CLSA-2025-1764321653, CLSA-2025-1764584370, CLSA-2026-1776935009, CLSA-2026-1777287060, CLSA-2026-1777479919, CLSA-2026-1781169600, DEBIAN-CVE-2025-40778, GHSA-xmqp-6cj2-2hh3, MINI-p2qp-c3w4-xr34, OESA-2025-2759, OESA-2025-2842, OESA-2025-2843, OESA-2025-2875, OESA-2026-1601, OESA-2026-1602, RHSA-2025:19835, RHSA-2025:21735, RHSA-2025:21736, RHSA-2025:22205, RLSA-2025:19835, SUSE-SU-2025:3976-1, UBUNTU-CVE-2025-40778

## What is CVE-2025-40778?

CVE-2025-40778 is a high-severity vulnerability in ISC BIND 9, published on 22 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-349 (Acceptance of Extraneous Untrusted Data With Trusted Data)

## Which versions are affected by CVE-2025-40778?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bind` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-chroot` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-devel` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-export-devel` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-export-libs` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-libs` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-libs-lite` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-license` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-lite-devel` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-devel` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-libs` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-utils` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-sdb` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-sdb-chroot` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-utils` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `python3-bind` | AlmaLinux:8 | All versions | 32:9.11.36-16.el8_10.6 |
| `bind` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-chroot` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-export-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-libs` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-libs-lite` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-libs-lite-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-license` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-lite-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-libs` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-utils` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-pkcs11-utils-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-sdb` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-sdb-chroot` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-sdb-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |
| `bind-utils` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-16.el8_10.6 |

## How do I fix CVE-2025-40778?

Upgrade to a fixed version.

## Is CVE-2025-40778 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-40778 exists.

Public exploit code:

- POC CVE-2025-40778: Cache Poisoning BIND 9 👾 (github_poc): https://github.com/nehkark/CVE-2025-40778
- Forensic triage of DNS cache poisoning in legacy hardware. Includes PCAP analysis of 839-byte unsolicited record injections, CVE-2025-40778 mapping, and remediation via hardened Unbound (DoT) on Arch Linux. (github_poc): https://github.com/nicholasC03/DNS-Poisoning-Triage-Lab
- Proof of Concept for CVE-2025-40778: BIND 9 DNS Cache Poisoning via unsolicited Additional Section records. (github_poc): https://github.com/sirbuvladste/BIND-9-Cache-Poisoning-PoC---CVE-2025-40778

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40778 and fix it if it is affected.

What it is: CVE-2025-40778 is a high-severity vulnerability in ISC BIND 9, published on 22 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-40778 exists.

Affected product: ISC BIND 9. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-40778/ (Markdown: https://insights.sbomify.com/CVE-2025-40778/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40778
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40778
- OSV: https://osv.dev/vulnerability/CVE-2025-40778

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40778/
Summaries are generated and may contain mistakes; the official description above is the record.