# CVE-2026-40528: OpenSC < 0.27.0 Buffer Overrun in do_key_value() via profile.c

> Attackers can corrupt memory and potentially execute code by supplying a crafted profile configuration file to OpenSC during pkcs15-init invocation.

- **Severity:** Low 1.0 (`CVSS:4.0/AV:P/AC:H/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/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:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 29 May 2026
- **Updated:** 14 Jul 2026
- **Also known as:** AZL-89147, CLSA-2026-1781088266, GHSA-vxjj-52h8-95w5

## What is CVE-2026-40528?

CVE-2026-40528 is a low-severity memory corruption vulnerability in Opensc Project Opensc, published on 29 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

OpenSC before 0.27.0, fixed in commit 0358817, contains a stack and heap buffer overrun vulnerability in the do_key_value() function in src/pkcs15init/profile.c that allows attackers to corrupt memory by supplying a crafted profile configuration file. During pkcs15-init invocation, a key value entry beginning with '=' followed by more than sizeof(keybuf) characters is copied into keybuf via memcpy without a length check, causing both stack and heap buffer overruns.

Weakness: CWE-122 (Heap-based Buffer Overflow), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-40528?

It affects 1 product.


Products: Opensc Project Opensc.

## How do I fix CVE-2026-40528?

Apply the vendor's patch.

## Is CVE-2026-40528 being exploited?

There is no known exploitation of CVE-2026-40528 in the wild and no public exploit code.

## Other vulnerabilities in Opensc Project Opensc

- [CVE-2021-34193](https://insights.sbomify.com/CVE-2021-34193/): Memory corruption in n/a (high 7.5)
- [CVE-2019-16058](https://insights.sbomify.com/CVE-2019-16058/): Memory corruption in n/a (high 7.5)
- [CVE-2019-6502](https://insights.sbomify.com/CVE-2019-6502/): Denial of service in n/a (high 7.5)
- [CVE-2023-2977](https://insights.sbomify.com/CVE-2023-2977/): Memory corruption in OpenSC (high 7.1)
- [CVE-2019-20792](https://insights.sbomify.com/CVE-2019-20792/): Use after free in n/a (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40528 and fix it if it is affected.

What it is: CVE-2026-40528 is a low-severity memory corruption vulnerability in Opensc Project Opensc, published on 29 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-40528 in the wild and no public exploit code.

Affected product: Opensc Project Opensc. 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-2026-40528/ (Markdown: https://insights.sbomify.com/CVE-2026-40528/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40528
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40528
- OSV: https://osv.dev/vulnerability/CVE-2026-40528

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40528/
Summaries are generated and may contain mistakes; the official description above is the record.