CVE-2021-34193
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedStack overflow vulnerability in OpenSC smart card middleware before 0.23 via crafted responses to APDUs.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA stack-based buffer overflow vulnerability exists in OpenSC smart card middleware versions prior to 0.23. The vulnerability is triggered when processing crafted APDU (Application Protocol Data Unit) responses from a smart card, causing a stack overflow that could enable denial of service or potentially remote code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 0.22.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed OpenSC versionRun 'opensc-tool --version' or check via package manager (dpkg -l | grep opensc, rpm -qa | grep opensc, or brew list opensc)Affected if Version is lower than 0.22.0
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Verify OpenSC binaries are presentCheck for OpenSC executables in common locations: /usr/bin/opensc-tool, /usr/bin/pkcs15-tool, /usr/bin/pkcs11-tool, or check PATH with 'which opensc-tool'Affected if OpenSC binaries exist and version cannot be determined or is below 0.22.0
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Check for active smart card readersRun 'opensc-tool --list-readers' to see if any smart card readers are detected and if OpenSC can communicate with themAffected if Readers are present and OpenSC version is vulnerable (below 0.22.0)
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Identify processes using OpenSC librariesCheck for running processes that may use OpenSC: look for smart card daemons (pcscd), authentication agents using PKCS#11, or applications accessing smart cardsAffected if Processes actively using OpenSC to communicate with smart cards and the OpenSC version is below 0.22.0
You are affected if OpenSC version 0.22.0 or later is not installed and the system is used to process smart card APDU responses.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped0.22.0
Upgrade OpenSC to version 0.23 or later to obtain the patched version. Verify all smart card operations function correctly after the upgrade.
OpenSC 0.23 or later
- 1. Check the current installed version of OpenSC using 'opensc-tool --version' or your system's package manager
- 2. If running a version before 0.23, plan for upgrade during a maintenance window
- 3. For Linux systems using package managers: update via 'apt-get update && apt-get upgrade opensc' (Debian/Ubuntu) or 'yum update opensc' (RHEL/CentOS)
- 4. For other platforms, download OpenSC 0.23 or later from the official GitHub repository: https://github.com/OpenSC/OpenSC/releases
- 5. After upgrade, restart any smart card services or applications that use OpenSC
- 6. Verify the new version is installed: 'opensc-tool --version'
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-34193 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-34193 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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