# CVE-2026-87733: Other in mirage-crypto-ec

> Attackers can forge ECDSA signatures by using the point at infinity as a public key in mirage-crypto-ec, bypassing authentication checks.

- **Severity:** Medium 6.2 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Sep 2026
- **Updated:** 9 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-87733, GHSA-5v5p-5xxr-9xf8, OSEC-2026-13, UBUNTU-CVE-2026-87733

## What is CVE-2026-87733?

CVE-2026-87733 is a medium-severity vulnerability in OCaml mirage-crypto-ec, published on 9 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An issue was discovered in the mirage-crypto-ec function before 2.2.0 for OCaml. The ECDSA functions {P256,P384,P521}.Dsa.pub_of_octets accept 0x00, the encoding of the point at infinity, as a public key. With that public key, signatures can be forged without a private key.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-87733?


## How do I fix CVE-2026-87733?

Upgrade to a fixed version.

## Is CVE-2026-87733 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87733 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-87733 and fix it if it is affected.

What it is: CVE-2026-87733 is a medium-severity vulnerability in OCaml mirage-crypto-ec, published on 9 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87733 exists.

Affected product: OCaml mirage-crypto-ec. 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-2026-87733/ (Markdown: https://insights.sbomify.com/CVE-2026-87733/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-87733
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-87733
- OSV: https://osv.dev/vulnerability/CVE-2026-87733

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-87733/
Summaries are generated and may contain mistakes; the official description above is the record.