CVE-2026-34873 An issue was discovered in Mbed TLS 3.5.0 through 4.0.0.
Critical 9.1
Published
Updated
Check this codebase for CVE-2026-34873 and fix it if it is affected.
What it is: CVE-2026-34873 is a critical vulnerability in n/a, published on 1 Apr 2026.
Exploitation: There is no known exploitation of CVE-2026-34873 in the wild and no public exploit code.
Affected product: n/a. 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-2026-34873/ (Markdown: https://insights.sbomify.com/CVE-2026-34873/index.md)
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-34873?
CVE-2026-34873 is a critical vulnerability in n/a, published on 1 Apr 2026.
Official description
An issue was discovered in Mbed TLS 3.5.0 through 4.0.0. Client impersonation can occur while resuming a TLS 1.3 session.
Weakness: CWE-287
Which versions are affected by CVE-2026-34873?
It affects 1 product.
Products include Trustedfirmware Mbed Tls.
How do I fix CVE-2026-34873?
Upgrade to a fixed version.
Is CVE-2026-34873 being exploited?
There is no known exploitation of CVE-2026-34873 in the wild and no public exploit code.
Other vulnerabilities in n/a
Sources
Also known as DEBIAN-CVE-2026-34873, ECHO-fc34-8f29-f217, GHSA-q24g-gcpv-7264, ROOT-OS-DEBIAN-12-CVE-2026-34873, UBUNTU-CVE-2026-34873.