# CVE-2019-6471: A race condition when discarding malformed packets can cause BIND to exit with an assertion failure

> A race condition when discarding malformed packets causes BIND to exit, leading to denial of service for DNS services.

- **Severity:** Medium 5.9 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Oct 2019
- **Updated:** 17 Sep 2024
- **Also known as:** ALPINE-CVE-2019-6471, DEBIAN-CVE-2019-6471, GHSA-52fp-qxmc-8q94, RHSA-2019:1714, SUSE-SU-2019:2550-1, UBUNTU-CVE-2019-6471, USN-4026-1, openSUSE-SU-2019:2263-1, openSUSE-SU-2019:2265-1

## What is CVE-2019-6471?

CVE-2019-6471 is a medium-severity vulnerability in F5 Big-Ip Access Policy Manager, published on 9 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A race condition which may occur when discarding malformed packets can result in BIND exiting due to a REQUIRE assertion failure in dispatch.c. Versions affected: BIND 9.11.0 -> 9.11.7, 9.12.0 -> 9.12.4-P1, 9.14.0 -> 9.14.2. Also all releases of the BIND 9.13 development branch and version 9.15.0 of the BIND 9.15 development branch and BIND Supported Preview Edition versions 9.11.3-S1 -> 9.11.7-S1.

Weakness: CWE-617 (Reachable Assertion), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2019-6471?

It affects 17 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bind` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-chroot` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-export-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-libs` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-libs-lite` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-libs-lite-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-license` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-lite-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-libs` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-utils` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-utils-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-sdb` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-sdb-chroot` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-sdb-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-utils` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-utils-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `python3-bind` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-export-devel` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-export-libs` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-export-libs-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-libs-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-libs-lite-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-libs-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-pkcs11-utils-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-sdb-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind-utils-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 32:9.11.4-17.P2.el8_0.1 |
| `bind` | SUSE:Linux Enterprise Module for Basesystem 15 | All versions | 9.11.2-12.13.2 |
| `bind` | SUSE:Linux Enterprise Module for Basesystem 15 SP1 | All versions | 9.11.2-12.13.2 |

Products: F5 Big-Ip Access Policy Manager, F5 Big-Ip Advanced Firewall Manager, F5 Big-Ip Analytics, F5 Big-Ip Application Acceleration Manager, F5 Big-Ip Application Security Manager, F5 Big-Ip Domain Name System, F5 Big-Ip Edge Gateway, F5 Big-Ip Fraud Protection Service, F5 Big-Ip Global Traffic Manager, F5 Big-Ip Link Controller, F5 Big-Ip Local Traffic Manager, F5 Big-Ip Policy Enforcement Manager, F5 Big-Ip Webaccelerator, F5 Big-Iq Centralized Management, F5 Enterprise Manager, F5 Iworkflow, Isc Bind.

## How do I fix CVE-2019-6471?

Apply the vendor's patch.

## Is CVE-2019-6471 being exploited?

There is no known exploitation of CVE-2019-6471 in the wild and no public exploit code.

## Other vulnerabilities in F5 Big-Ip Access Policy Manager

- [CVE-2023-46747](https://insights.sbomify.com/CVE-2023-46747/): F5 BIG-IP Configuration Utility Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2022-1388](https://insights.sbomify.com/CVE-2022-1388/): F5 BIG-IP Missing Authentication (critical 9.8, exploited in the wild)
- [CVE-2021-22986](https://insights.sbomify.com/CVE-2021-22986/): F5 BIG-IP and BIG-IQ Centralized Management iControl REST Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2021-22991](https://insights.sbomify.com/CVE-2021-22991/): F5 BIG-IP Traffic Management Microkernel Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2020-5902](https://insights.sbomify.com/CVE-2020-5902/): F5 BIG-IP Traffic Management User Interface (TMUI) Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-6471 and fix it if it is affected.

What it is: CVE-2019-6471 is a medium-severity vulnerability in F5 Big-Ip Access Policy Manager, published on 9 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-6471 in the wild and no public exploit code.

Affected product: F5 Big-Ip Access Policy Manager. 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-2019-6471/ (Markdown: https://insights.sbomify.com/CVE-2019-6471/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-6471
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-6471
- OSV: https://osv.dev/vulnerability/CVE-2019-6471

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-6471/
Summaries are generated and may contain mistakes; the official description above is the record.