# CVE-2026-5187: Heap Out-of-Bounds Write in DecodeObjectId() in wolfSSL

> Heap out-of-bounds write in wolfSSL's ASN.1 decoder allows attackers to corrupt memory, potentially leading to code execution or crashes.

- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Apr 2026
- **Updated:** 14 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-5187, GHSA-98ww-gw4p-68m3, JLSEC-2026-714, UBUNTU-CVE-2026-5187

## What is CVE-2026-5187?

CVE-2026-5187 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 9 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-5187?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2026-5187?

Apply the vendor's patch.

## Is CVE-2026-5187 being exploited?

There is no known exploitation of CVE-2026-5187 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-2026-5187 and fix it if it is affected.

What it is: CVE-2026-5187 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 9 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5187 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-2026-5187/ (Markdown: https://insights.sbomify.com/CVE-2026-5187/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5187
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5187
- OSV: https://osv.dev/vulnerability/CVE-2026-5187

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5187/
Summaries are generated and may contain mistakes; the official description above is the record.