# CVE-2026-5466: wc_VerifyEccsiHash missing sanity check

> Attackers can forge ECCSI signatures to bypass authentication checks in wolfSSL due to missing scalar validation.

- **Severity:** High 7.6 (`CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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:** 10 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-5466, GHSA-47qf-hp3h-rwmm, JLSEC-2026-726, UBUNTU-CVE-2026-5466

## What is CVE-2026-5466?

CVE-2026-5466 is a high-severity vulnerability in Wolfssl Wolfssl, published on 10 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

wolfSSL's ECCSI signature verifier `wc_VerifyEccsiHash` decodes the `r` and `s` scalars from the signature blob via `mp_read_unsigned_bin` with no check that they lie in `[1, q-1]`. A crafted forged signature could verify against any message for any identity, using only publicly-known constants.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-5466?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2026-5466?

Apply the vendor's patch.

## Is CVE-2026-5466 being exploited?

There is no known exploitation of CVE-2026-5466 in the wild and no public exploit code.

## Other vulnerabilities in Wolfssl Wolfssl

- [CVE-2024-5991](https://insights.sbomify.com/CVE-2024-5991/): Buffer overread in domain name matching (critical 10.0)
- [CVE-2021-37155](https://insights.sbomify.com/CVE-2021-37155/): Security feature bypass in n/a (critical 9.8)
- [CVE-2020-36177](https://insights.sbomify.com/CVE-2020-36177/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2896](https://insights.sbomify.com/CVE-2014-2896/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2897](https://insights.sbomify.com/CVE-2014-2897/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5466 and fix it if it is affected.

What it is: CVE-2026-5466 is a high-severity vulnerability in Wolfssl Wolfssl, published on 10 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5466 in the wild and no public exploit code.

Affected product: Wolfssl Wolfssl. 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-2026-5466/ (Markdown: https://insights.sbomify.com/CVE-2026-5466/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5466
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5466
- OSV: https://osv.dev/vulnerability/CVE-2026-5466

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5466/
Summaries are generated and may contain mistakes; the official description above is the record.