# CVE-2021-34558: Denial of service in n/a > A malicious TLS server can cause a Go TLS client to panic due to improper public key type assertion, resulting in a denial of service. - **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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:** A user has to click or open something - **Fix available:** Yes - **Published:** 15 Jul 2021 - **Updated:** 4 Aug 2024 - **Also known as:** AZL-105164, AZL-105167, BIT-golang-2021-34558, DEBIAN-CVE-2021-34558, GHSA-hqrm-74p3-w275, GO-2021-0243, RHEA-2021:3287, RHSA-2021:3015, SUSE-SU-2021:2392-1, SUSE-SU-2021:2398-1, UBUNTU-CVE-2021-34558, openSUSE-SU-2021:1078-1, openSUSE-SU-2021:1079-1, openSUSE-SU-2021:2392-1, openSUSE-SU-2021:2398-1 ## What is CVE-2021-34558? CVE-2021-34558 is a medium-severity denial of service vulnerability in Fedoraproject Fedora, published on 15 Jul 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link. ### Official description The crypto/tls package of Go through 1.16.5 does not properly assert that the type of public key in an X.509 certificate matches the expected type when doing a RSA based key exchange, allowing a malicious TLS server to cause a TLS client to panic. Weakness: CWE-295 (Improper Certificate Validation) ## Which versions are affected by CVE-2021-34558? 2 open source packages ship an affected version, including golang and stdlib. It affects 6 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `golang` | Bitnami | All versions | 1.15.14, 1.16.6 | | `stdlib` | Go | All versions | 1.15.14, 1.16.6 | | `go-toolset-1.15` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-build` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-golang` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-golang-bin` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-golang-docs` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-golang-misc` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-golang-race` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-golang-src` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-golang-tests` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-runtime` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `go-toolset-1.15-scldevel` | Red Hat:devtools:2021 | All versions | 0:1.15.14-1.el7_9 | | `rosa` | Red Hat:openshift_service_on_aws:1::el8 | All versions | 0:1.1.1-51c4a5e.el8 | | `rosa-redistributable` | Red Hat:openshift_service_on_aws:1::el8 | All versions | 0:1.1.1-51c4a5e.el8 | | `go1.15` | SUSE:Linux Enterprise Module for Development Tools 15 SP2 | All versions | 1.15.14-1.36.1 | | `go1.16` | SUSE:Linux Enterprise Module for Development Tools 15 SP2 | All versions | 1.16.6-1.20.1 | | `go1.15` | SUSE:Linux Enterprise Module for Development Tools 15 SP3 | All versions | 1.15.14-1.36.1 | | `go1.16` | SUSE:Linux Enterprise Module for Development Tools 15 SP3 | All versions | 1.16.6-1.20.1 | | `go1.15` | openSUSE:Leap 15.2 | All versions | 1.15.14-lp152.23.1 | | `go1.16` | openSUSE:Leap 15.2 | All versions | 1.16.6-lp152.5.1 | | `go1.15` | openSUSE:Leap 15.3 | All versions | 1.15.14-1.36.1 | | `go1.16` | openSUSE:Leap 15.3 | All versions | 1.16.6-1.20.1 | Products: Fedoraproject Fedora, Golang Go, Netapp Cloud Insights Telegraf, Netapp Storagegrid, Netapp Trident, Oracle Timesten In-Memory Database. ## How do I fix CVE-2021-34558? Upgrade golang to a fixed version for your release line: 1.15.14 or 1.16.6. ## Is CVE-2021-34558 being exploited? There is no known exploitation of CVE-2021-34558 in the wild and no public exploit code. Public exploit code: - https://github.com/alexzorin/cve-2021-34558 (github_poc): https://github.com/alexzorin/cve-2021-34558 ## Other vulnerabilities in Fedoraproject Fedora - [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild) - [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild) - [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild) - [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild) - [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-34558 and fix it if it is affected. What it is: CVE-2021-34558 is a medium-severity denial of service vulnerability in Fedoraproject Fedora, published on 15 Jul 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2021-34558 in the wild and no public exploit code. Affected packages and fixed versions: - golang (Bitnami): affected all versions; fixed in 1.15.14, 1.16.6 - stdlib (Go): affected all versions; fixed in 1.15.14, 1.16.6 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-2021-34558/ (Markdown: https://insights.sbomify.com/CVE-2021-34558/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34558 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34558 - OSV: https://osv.dev/vulnerability/CVE-2021-34558 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-34558/ Summaries are generated and may contain mistakes; the official description above is the record.