# CVE-2026-103531: OpenSC card-setcos.c setcos_construct_fci_44 stack-based overflow

> A stack-based buffer overflow in OpenSC allows remote attackers to execute arbitrary code or cause denial of service via manipulated arguments.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 1 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** AZL-105342, CLSA-2026-1791470029, DEBIAN-CVE-2026-103531, GHSA-m2qg-x6vj-xmrg, UBUNTU-CVE-2026-103531

## What is CVE-2026-103531?

CVE-2026-103531 is a medium-severity memory corruption vulnerability in OpenSC, published on 1 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

A flaw has been found in OpenSC up to 0.27.1. The impacted element is the function setcos_construct_fci_44 of the file src/libopensc/card-setcos.c. Executing a manipulation of the argument type_attr can lead to stack-based buffer overflow. The attack can be launched remotely. This patch is called ad730304052937c32b4eb489a06835ac6123632c. It is best practice to apply a patch to resolve this issue.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-103531?


## How do I fix CVE-2026-103531?

Apply the vendor's patch.

## Is CVE-2026-103531 being exploited?

There is no known exploitation of CVE-2026-103531 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103531 and fix it if it is affected.

What it is: CVE-2026-103531 is a medium-severity memory corruption vulnerability in OpenSC, published on 1 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-103531 in the wild and no public exploit code.

Affected product: 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-2026-103531/ (Markdown: https://insights.sbomify.com/CVE-2026-103531/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103531
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103531
- OSV: https://osv.dev/vulnerability/CVE-2026-103531

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103531/
Summaries are generated and may contain mistakes; the official description above is the record.