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Enterprise LinuxOperating system · Redhat

CVE-2023-40660

MEDIUM · 6.6 CVSS v3.1 Published 2023-11-06
Fix available
A fix is available. Upgrade to after 0.23.0 or later.
See remediation →
69/100
Remediation priority · Elevated
No privileges

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 · unedited
A flaw was found in OpenSC packages that allow a potential PIN bypass. When a token/card is authenticated by one process, it can perform cryptographic operations in other processes when an empty zero-length pin is passed. This issue poses a security risk, particularly for OS logon/screen unlock and for small, permanently connected tokens to computers. Additionally, the token can internally track login status. This flaw allows an attacker to gain unauthorized access, carry out malicious actions, or compromise the system without the user's awareness.

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 confidence

OpenSC contains a PIN bypass vulnerability where an authenticated token can perform cryptographic operations in other processes when an empty zero-length PIN is passed, exploiting the token's internal login status tracking.

MitigationUpdate OpenSC to the patched version and review OS logon/screen unlock configurations to ensure they do not rely solely on token internal login state; consider additional authentication controls for high-risk scenarios.

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
Enterprise LinuxOperating system
Affected:= 8.0= 9.0
OpenscApplication
Affected:<= 0.23.0

CVSS 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
Physical
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:P/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check if OpenSC is installed
    Run 'rpm -qa | grep opensc' on RHEL or 'opensc-tool --version' to verify OpenSC package presence
    Affected if OpenSC package is found on the system
  2. Determine installed OpenSC version
    Run 'rpm -q --qf '%{VERSION}-%{RELEASE}' opensc' or 'opensc-tool --version' and compare to <= 0.23.0
    Affected if Version is 0.23.0 or lower, or for RHEL if versions 8.0 or 9.0 match the installed package
  3. Identify applications using OpenSC for smart card authentication
    Review system authentication configuration files in /etc/pam.d/ and check for 'pam_pkcs11' or 'opensc' module usage in login configs
    Affected if PAM configuration relies on OpenSC for system login, screen unlock, or sudo authentication
  4. Audit for custom scripts or applications passing PINs to OpenSC tools
    Search for scripts using 'pkcs15-crypt', 'opensc-tool', or similar with PIN arguments, particularly looking for empty string or zero-length PIN handling
    Affected if Any custom authentication scripts exist that pass empty or zero-length PIN values to OpenSC tools
  5. Review system logs for authentication anomalies
    Check /var/log/secure (RHEL) or journalctl for pam_pkcs11 and OpenSC related authentication events, looking for successful auth with unusual PIN lengths
    Affected if Logs show successful smart card authentications that may have used empty PINs

A system is affected if OpenSC version 0.23.0 or lower (or RHEL 8.0/9.0 opensc packages) is installed AND the system uses smart card authentication via OpenSC for login or privilege escalation, particularly if custom scripts handle PINs.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to a release after 0.23.0
Interim mitigation

Update OpenSC to the patched version and review OS logon/screen unlock configurations to ensure they do not rely solely on token internal login state; consider additional authentication controls for high-risk scenarios.

Recommended fix High confidence

OpenSC 0.24.0 or later / Red Hat Enterprise Linux opensc packages via RHSA

  1. 1. Identify the OpenSC package version currently installed: `rpm -qa | grep opensc`
  2. 2. For upstream OpenSC: Download and install OpenSC version 0.24.0 or later from the official GitHub releases (https://github.com/OpenSC/OpenSC/releases)
  3. 3. For Red Hat Enterprise Linux 8/9: Run `sudo dnf check-update` to check for available security updates
  4. 4. Apply the security update: `sudo dnf update opensc` or `sudo yum update opensc`
  5. 5. Verify the updated version: `rpm -qa | grep opensc` to confirm version 0.24.0 or newer is installed
  6. 6. If using smart cards for system authentication, test login/unlock functionality to ensure the PIN bypass vulnerability is remediated
Caveat Upgrading OpenSC may affect smart card reader compatibility or authentication behavior; test thoroughly in a non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Enterprise Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA3.0 h
14.0 hours of engineering $2,400
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-40660 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data