# CVE-2020-10772: Denial of service in unbound > Incomplete fix allows Unbound DNS resolver to amplify queries, enabling denial of service attacks against targets. - **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:** 27 Nov 2020 - **Updated:** 4 Aug 2024 - **Also known as:** GHSA-g6qm-p3jr-vj64, RHSA-2020:2642 ## What is CVE-2020-10772? CVE-2020-10772 is a high-severity denial of service vulnerability in Nlnetlabs Unbound, published on 27 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description An incomplete fix for CVE-2020-12662 was shipped for Unbound in Red Hat Enterprise Linux 7, as part of erratum RHSA-2020:2414. Vulnerable versions of Unbound could still amplify an incoming query into a large number of queries directed to a target, even with a lower amplification ratio compared to versions of Unbound that shipped before the mentioned erratum. This issue is about the incomplete fix for CVE-2020-12662, and it does not affect upstream versions of Unbound. Weakness: CWE-400 (Uncontrolled Resource Consumption), CWE-406 (Insufficient Control of Network Message Volume (Network Amplification)) ## Which versions are affected by CVE-2020-10772? It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `unbound` | Red Hat:enterprise_linux:7::client | All versions | 0:1.6.6-5.el7_8 | | `unbound-debuginfo` | Red Hat:enterprise_linux:7::client | All versions | 0:1.6.6-5.el7_8 | | `unbound-devel` | Red Hat:enterprise_linux:7::client | All versions | 0:1.6.6-5.el7_8 | | `unbound-libs` | Red Hat:enterprise_linux:7::client | All versions | 0:1.6.6-5.el7_8 | | `unbound-python` | Red Hat:enterprise_linux:7::client | All versions | 0:1.6.6-5.el7_8 | | `unbound` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.6.6-5.el7_8 | | `unbound-debuginfo` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.6.6-5.el7_8 | | `unbound-devel` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.6.6-5.el7_8 | | `unbound-libs` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.6.6-5.el7_8 | | `unbound-python` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.6.6-5.el7_8 | | `unbound` | Red Hat:enterprise_linux:7::server | All versions | 0:1.6.6-5.el7_8 | | `unbound-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1.6.6-5.el7_8 | | `unbound-devel` | Red Hat:enterprise_linux:7::server | All versions | 0:1.6.6-5.el7_8 | | `unbound-libs` | Red Hat:enterprise_linux:7::server | All versions | 0:1.6.6-5.el7_8 | | `unbound-python` | Red Hat:enterprise_linux:7::server | All versions | 0:1.6.6-5.el7_8 | | `unbound` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.6.6-5.el7_8 | | `unbound-debuginfo` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.6.6-5.el7_8 | | `unbound-devel` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.6.6-5.el7_8 | | `unbound-libs` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.6.6-5.el7_8 | | `unbound-python` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.6.6-5.el7_8 | Products: Nlnetlabs Unbound. ## How do I fix CVE-2020-10772? Apply the vendor's patch. ## Is CVE-2020-10772 being exploited? There is no known exploitation of CVE-2020-10772 in the wild and no public exploit code. ## Other vulnerabilities in Nlnetlabs Unbound - [CVE-2026-81642](https://insights.sbomify.com/CVE-2026-81642/): Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY (critical 9.1) - [CVE-2026-33278](https://insights.sbomify.com/CVE-2026-33278/): Possible arbitrary code execution during DNSSEC validation (critical 9.1) - [CVE-2026-42944](https://insights.sbomify.com/CVE-2026-42944/): Heap overflow with multiple NSID, COOKIE, PADDING EDNS options (high 8.7) - [CVE-2026-42959](https://insights.sbomify.com/CVE-2026-42959/): Crash during DNSSEC validation of malicious content (high 8.7) - [CVE-2026-82717](https://insights.sbomify.com/CVE-2026-82717/): CNAME synthesis could lead to heap corruption (high 8.4) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-10772 and fix it if it is affected. What it is: CVE-2020-10772 is a high-severity denial of service vulnerability in Nlnetlabs Unbound, published on 27 Nov 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-2020-10772 in the wild and no public exploit code. Affected product: Nlnetlabs Unbound. 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-2020-10772/ (Markdown: https://insights.sbomify.com/CVE-2020-10772/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-10772 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-10772 - OSV: https://osv.dev/vulnerability/CVE-2020-10772 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-10772/ Summaries are generated and may contain mistakes; the official description above is the record.