# CVE-2026-0819: Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes

> Stack buffer overflow in wolfSSL PKCS7 encoding allows code execution or DoS if applications allow untrusted input to control signed attribute sizes.

- **Severity:** Low 2.2 (`CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U`)
- **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:** 19 Mar 2026
- **Updated:** 19 Mar 2026
- **Also known as:** DEBIAN-CVE-2026-0819, GHSA-3cr6-hpf3-2hmg, JLSEC-2026-691, UBUNTU-CVE-2026-0819

## What is CVE-2026-0819?

CVE-2026-0819 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 19 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd->signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7->signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions.

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-0819?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2026-0819?

Apply the vendor's patch.

## Is CVE-2026-0819 being exploited?

There is no known exploitation of CVE-2026-0819 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-2026-0819 and fix it if it is affected.

What it is: CVE-2026-0819 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 19 Mar 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-2026-0819 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-2026-0819/ (Markdown: https://insights.sbomify.com/CVE-2026-0819/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-0819
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-0819
- OSV: https://osv.dev/vulnerability/CVE-2026-0819

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-0819/
Summaries are generated and may contain mistakes; the official description above is the record.