Is CVE-2026-103531 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-103531 being exploited in the wild.

How severe is CVE-2026-103531?

Medium severity, with a CVSS score of 5.5, published 1 October 2026.

Is there a fix for CVE-2026-103531?

Yes: fixed in OpenSC 0.27.2 or later (commit ad730304052937c32b4eb489a06835ac6123632c). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-103531 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-103531?

Check whether you run OpenSC at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-103531: OpenSC stack-based buffer overflow in setcos_construct_fci_44

CVE-2026-103531 · Severity: medium · CVSS 5.5 · Published 2026-10-01

OpenSC is open-source middleware for smart card operations. A stack-based buffer overflow in its setcos module can be triggered by manipulating attribute fields in card responses, allowing an attacker with network access to corrupt memory and potentially execute code or crash the application.

Vendors: OpenSC.

Quick answers

Is CVE-2026-103531 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-103531 being exploited in the wild.
How severe is CVE-2026-103531?: Medium severity, with a CVSS score of 5.5, published 1 October 2026.
Which products and versions are affected?: OpenSC up to 0.27.1.
Is there a fix for CVE-2026-103531?: Yes: fixed in OpenSC 0.27.2 or later (commit ad730304052937c32b4eb489a06835ac6123632c). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-103531 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-103531?: Check whether you run OpenSC at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: OpenSC 0.27.2 or later (commit ad730304052937c32b4eb489a06835ac6123632c)

Technical details

A stack-based buffer overflow exists in the setcos_construct_fci_44 function in src/libopensc/card-setcos.c, where type_attr, sec_attr, and prop_attr are copied into a fixed 64-byte stack buffer without length validation. An attacker can supply malicious or corrupted attribute lengths (reachable through attacker-controlled card responses or fuzzing) to overflow the buffer. The vulnerability requires network access to respond with crafted card data.

Affected products

OpenSC OpenSC up to 0.27.1

Timeline

2026-10-01: disclosed

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.