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CVE Record

CVE-2021-34193: Stack overflow vulnerability in OpenSC smart card middleware before 0.23 via crafted responses to APDUs.

Stack overflow vulnerability in OpenSC smart card middleware before 0.23 via crafted responses to APDUs.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-34193 is a stack overflow in OpenSC smart card middleware before version 0.23. A malicious or faulty smart card response could crash or potentially destabilize software that processes APDU responses through OpenSC. The sources do not provide CVSS, confirmed impact beyond stack overflow, or active exploitation evidence.

Executive priority

Treat this as targeted patch hygiene for environments that rely on smart cards or hardware tokens. Urgency rises where OpenSC supports authentication, signing, or privileged workflows. Lack of CVSS and exploitation evidence limits confidence in business impact.

Technical view

OpenSC versions before 0.23 are reported vulnerable to stack overflow when handling crafted APDU responses. The CVE record links multiple OSS-Fuzz issues, indicating fuzz-discovered parsing or response-handling failures. The bundle does not identify specific modules, reachable applications, privileges, or a weaponized exploit path.

Likely exposure

Exposure is most likely on endpoints, servers, or authentication workflows using OpenSC for smart cards, tokens, or PKCS#11-backed identity operations. Systems not using OpenSC or not processing smart card APDU responses are less likely exposed.

Exploitation context

No CISA KEV listing is provided, and the source bundle does not cite in-the-wild exploitation. Exploitation would require crafted APDU responses reaching vulnerable OpenSC handling, likely through smart card or token interaction rather than ordinary network traffic.

Researcher notes

The public bundle is thin: it names OpenSC before 0.23 and crafted APDU responses, but omits CVSS, CWE, affected CPEs, code locations, and impact detail. OSS-Fuzz references support fuzz-discovered memory safety issues but should be reviewed before asserting exploitability.

Mitigation direction

  • Inventory OpenSC installations and identify versions before 0.23.
  • Upgrade OpenSC to 0.23 or a supported vendor-fixed package.
  • Apply relevant distribution security updates, including Debian LTS guidance where applicable.
  • Restrict use of untrusted smart cards or tokens until updated.
  • Monitor vendor and distribution advisories for additional guidance.

Validation and detection

  • Check installed OpenSC package versions across managed endpoints and servers.
  • Confirm smart card, token, or PKCS#11 workflows depend on OpenSC.
  • Review package manager history for OpenSC security updates.
  • Prioritize systems used for authentication, signing, or privileged access.
  • Track whether vendor advisories map this CVE to deployed packages.
Prepared
Confidence
medium
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2021-34193 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
14Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.