# CVE-2020-8616: BIND does not sufficiently limit the number of fetches performed when processing referrals

> Attackers can degrade performance or launch reflection attacks by causing a recursing BIND server to issue excessive fetches via crafted referrals.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** 19 May 2020
- **Updated:** 16 Sep 2024
- **Also known as:** ALPINE-CVE-2020-8616, DEBIAN-CVE-2020-8616, GHSA-rc96-hg8v-6p4g, RHSA-2020:3272, UBUNTU-CVE-2020-8616

## What is CVE-2020-8616?

CVE-2020-8616 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 19 May 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A malicious actor who intentionally exploits this lack of effective limitation on the number of fetches performed when processing referrals can, through the use of specially crafted referrals, cause a recursing server to issue a very large number of fetches in an attempt to process the referral. This has at least two potential effects: The performance of the recursing server can potentially be degraded by the additional work required to perform these fetches, and The attacker can exploit this behavior to use the recursing server as a reflector in a reflection attack with a high amplification factor.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-8616?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bind` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-chroot` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-debuginfo` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-devel` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-export-devel` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-export-libs` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-libs` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-libs-lite` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-license` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-lite-devel` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11-devel` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11-libs` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11-utils` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-sdb` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-sdb-chroot` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-utils` | Red Hat:rhel_eus:7.7::computenode | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-chroot` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-debuginfo` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-devel` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-export-devel` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-export-libs` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-libs` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-libs-lite` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-license` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-lite-devel` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11-devel` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11-libs` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-pkcs11-utils` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-sdb` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-sdb-chroot` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |
| `bind-utils` | Red Hat:rhel_eus:7.7::server | All versions | 32:9.11.4-9.P2.el7_7.2 |

Products: Debian Debian Linux, Isc Bind.

## How do I fix CVE-2020-8616?

Apply the vendor's patch.

## Is CVE-2020-8616 being exploited?

There is no known exploitation of CVE-2020-8616 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-8616 and fix it if it is affected.

What it is: CVE-2020-8616 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 19 May 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-2020-8616 in the wild and no public exploit code.

Affected product: Debian Debian 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-2020-8616/ (Markdown: https://insights.sbomify.com/CVE-2020-8616/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8616
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8616
- OSV: https://osv.dev/vulnerability/CVE-2020-8616

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8616/
Summaries are generated and may contain mistakes; the official description above is the record.