# CVE-2026-10275: OpenSC pkcs11-tool buffer overflow in test_kpgen_certwrite

Source: https://junglewise.ai/threats/cve-2026-10275-opensc-pkcs11-tool-buffer-overflow-in-test-kpgen-certwrite  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-01. Updated: 2026-06-01  
License: CC BY 4.0 with a link back

CVE-2026-10275 · Severity: medium · CVSS 5 · Published 2026-06-01

OpenSC is an open-source suite of tools and libraries for interacting with smart cards and security tokens. A vulnerability in its pkcs11-tool component could allow a buffer overflow to occur during key generation or certificate writing operations. If exploited, this could lead to a service crash or potentially allow unauthorized code execution, though the attack is considered difficult to perform and requires specific user interaction.

Technologies: [OpenSC Project OpenSC](https://junglewise.ai/threats/technologies/opensc). Vendors: [OpenSC Project](https://junglewise.ai/threats/vendors/opensc-project).

## Quick answers

**Is CVE-2026-10275 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-10275 being exploited in the wild.

**How severe is CVE-2026-10275?** Medium severity, with a CVSS score of 5, published 1 June 2026.

**Which products and versions are affected?** OpenSC Project OpenSC up to 0.26.1.

**Is there a fix for CVE-2026-10275?** A patch was published on 2026-05-15: Fix merged into OpenSC master branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-10275 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-10275?** Check whether you run OpenSC Project 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.

## Technical details

A classic buffer overflow (CWE-120) exists in OpenSC versions up to 0.26.1 within the pkcs11-tool utility. The flaw is located in the test_kpgen_certwrite function in src/tools/pkcs11-tool.c, where the application fails to properly validate the length of an object ID before copying it into a fixed-size buffer (opt_object_id). An attacker could exploit this by providing a specially crafted URI or object ID that exceeds the buffer's capacity. While the attack vector is listed as remote, it carries high complexity and requires user interaction. A patch has been merged into the master branch (commit 814f745) which adds explicit bounds checking against the size of the destination buffer.

## Affected products

- OpenSC OpenSC up to 0.26.1

## Timeline

- 2026-05-11: disclosed: Issue reported on GitHub
- 2026-05-15: patched: Fix merged into OpenSC master branch
- 2026-06-01: advisory: CVE-2026-10275 published

## References

- [https://github.com/OpenSC/OpenSC/](https://github.com/OpenSC/OpenSC/)
- [https://github.com/OpenSC/OpenSC/commit/814f745b3b6d100295f65f1935edd33d520d33ab](https://github.com/OpenSC/OpenSC/commit/814f745b3b6d100295f65f1935edd33d520d33ab)
- [https://github.com/OpenSC/OpenSC/issues/3682](https://github.com/OpenSC/OpenSC/issues/3682)
- [https://github.com/OpenSC/OpenSC/pull/3684](https://github.com/OpenSC/OpenSC/pull/3684)
- [https://pan.baidu.com/s/1nrZPKDz2eAcCpsaFiIRlrg](https://pan.baidu.com/s/1nrZPKDz2eAcCpsaFiIRlrg)
- [https://vuldb.com/cve/CVE-2026-10275](https://vuldb.com/cve/CVE-2026-10275)
- [https://vuldb.com/submit/825403](https://vuldb.com/submit/825403)

## Related threats

- [OpenSC stack buffer overflow in PIV card history processing](https://junglewise.ai/threats/cve-2026-40510-opensc-stack-buffer-overflow-in-piv-card-history-processing)
- [OpenSC libopensc uninitialized variables in card detection](https://junglewise.ai/threats/cve-2025-13763-opensc-libopensc-uninitialized-variables-in-card-detection)