# CVE-2020-8623: A flaw in native PKCS#11 code can lead to a remotely triggerable assertion failure in pk11.c

> An attacker can cause a remote crash in BIND DNS servers by sending crafted queries if native PKCS#11 support is enabled and RSA keys are used.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/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:** 21 Aug 2020
- **Updated:** 17 Sep 2024
- **Also known as:** ALPINE-CVE-2020-8623, DEBIAN-CVE-2020-8623, GHSA-3hh5-h95j-2cw7, UBUNTU-CVE-2020-8623

## What is CVE-2020-8623?

CVE-2020-8623 is a high-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 21 Aug 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In BIND 9.10.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.10.5-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker that can reach a vulnerable system with a specially crafted query packet can trigger a crash. To be vulnerable, the system must: * be running BIND that was built with "--enable-native-pkcs11" * be signing one or more zones with an RSA key * be able to receive queries from a possible attacker

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2020-8623?

It affects 7 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Isc Bind, Netapp Steelstore Cloud Integrated Storage, Opensuse Leap, Synology Dns Server.

## How do I fix CVE-2020-8623?

Upgrade to a fixed version.

## Is CVE-2020-8623 being exploited?

There is no known exploitation of CVE-2020-8623 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-8623 and fix it if it is affected.

What it is: CVE-2020-8623 is a high-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 21 Aug 2020. 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-2020-8623 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2020-8623/ (Markdown: https://insights.sbomify.com/CVE-2020-8623/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8623
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8623
- OSV: https://osv.dev/vulnerability/CVE-2020-8623

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8623/
Summaries are generated and may contain mistakes; the official description above is the record.