CVE-2026-87866 wolfSSL public-key pinning bypass
Critical 9.1
Published
Updated
Check this codebase for CVE-2026-87866 and fix it if it is affected.
What it is: CVE-2026-87866 is a critical vulnerability in curl, published on 20 Oct 2026.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87866 exists.
Affected product: curl. 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-2026-87866/ (Markdown: https://insights.sbomify.com/CVE-2026-87866/index.md)
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-87866?
CVE-2026-87866 is a critical vulnerability in curl, published on 20 Oct 2026.
Official description
When built with wolfSSL, curl can successfully validate a pinned public key hash against a key the TLS peer does not possess. During the TLS handshake, wolfSSL validates the connection, but curl's subsequent re-parsing of the same certificate - tricked by a manipulated validity length field - extracts and matches a different embedded key, incorrectly authorizing the pinned public key.
Weakness: CWE-295
Which versions are affected by CVE-2026-87866?
How do I fix CVE-2026-87866?
Upgrade to a fixed version.
Is CVE-2026-87866 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87866 exists.
Sources
Also known as ALPINE-CVE-2026-87866, AZL-109920, AZL-109953, AZL-110028, AZL-110133, AZL-110211 and 6 more.