CVE-2023-2977 – This vulnerability in OpenSC allows attackers t... (How to Fix)

Q: What is the severity of CVE-2023-2977?

CVE-2023-2977 has a CVSS score of 7.1 (HIGH). This vulnerability in OpenSC allows attackers to trigger a heap-based buffer out-of-bounds read by sending a specially crafted smart card package with malformed ASN.1 context. The flaw can cause crashes, information leaks, or potentially more severe damage. Anyone using OpenSC for smart card authentication or cryptographic operations is affected.

📋 TL;DR

This vulnerability in OpenSC allows attackers to trigger a heap-based buffer out-of-bounds read by sending a specially crafted smart card package with malformed ASN.1 context. The flaw can cause crashes, information leaks, or potentially more severe damage. Anyone using OpenSC for smart card authentication or cryptographic operations is affected.

💻 Affected Systems

Products:

OpenSC

Versions: All versions before 0.23.0

Operating Systems: Linux, Windows, macOS - any OS using OpenSC

Default Config Vulnerable: ⚠️ Yes

Notes: Vulnerable when OpenSC processes smart card packages via the cardos_have_verifyrc_package function.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Information disclosure leading to credential theft, privilege escalation, or remote code execution depending on memory layout and exploitation techniques.

🟠

Likely Case

Application crashes (especially with ASAN enabled) and potential information leaks from heap memory.

🟢

If Mitigated

Limited impact with proper smart card validation and network segmentation in place.

🌐 Internet-Facing: LOW - Typically requires smart card interaction which isn't internet-exposed.

🏢 Internal Only: MEDIUM - Internal systems using OpenSC for smart card authentication could be targeted.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires ability to supply malformed smart card packages to the vulnerable function.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: OpenSC 0.23.0 and later

Vendor Advisory: https://access.redhat.com/security/cve/CVE-2023-2977

Restart Required: Yes

Instructions:

1. Update OpenSC to version 0.23.0 or later. 2. For Linux: Use package manager (apt-get update && apt-get upgrade opensc). 3. For Windows: Download latest installer from OpenSC website. 4. Restart services using OpenSC.

🔧 Temporary Workarounds

Disable vulnerable card drivers

all

Temporarily disable CardOS card driver if not required

# Edit OpenSC configuration to remove or comment CardOS driver

🧯 If You Can't Patch

Implement network segmentation to isolate smart card authentication systems
Monitor for crashes in OpenSC processes and investigate any anomalies

🔍 How to Verify

Check if Vulnerable:

Check OpenSC version: opensc-tool -v | grep 'OpenSC'

Check Version:

opensc-tool -v

Verify Fix Applied:

Verify version is 0.23.0 or higher: opensc-tool -v

📡 Detection & Monitoring

Log Indicators:

OpenSC process crashes
ASAN error messages in system logs
Unexpected smart card authentication failures

Network Indicators:

Unusual smart card authentication attempts
Malformed smart card protocol traffic

SIEM Query:

process_name:"opensc" AND (event_type:crash OR error_message:"buffer overflow" OR error_message:"ASAN")

📊 Metadata

CVE ID: CVE-2023-2977

CVSS v3 Score: 7.1 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

CWE: CWE-119

Published: June 1, 2023

Last Updated: November 3, 2025

🔗 References

https://access.redhat.com/security/cve/CVE-2023-2977 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2211088 Issue Tracking,Third Party Advisory
https://github.com/OpenSC/OpenSC/issues/2785 Issue Tracking,Patch
https://github.com/OpenSC/OpenSC/pull/2787 Patch
https://lists.debian.org/debian-lts-announce/2023/06/msg00025.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FJD4Q4AJSGE5UIJI7OUYZY4HGGCVYQNI/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LAR54OV6EHA56B4XJF6RNPQ4HJ2ITU66/
https://access.redhat.com/security/cve/CVE-2023-2977 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2211088 Issue Tracking,Third Party Advisory
https://github.com/OpenSC/OpenSC/issues/2785 Issue Tracking,Patch
https://github.com/OpenSC/OpenSC/pull/2787 Patch
https://lists.debian.org/debian-lts-announce/2023/06/msg00025.html
https://lists.debian.org/debian-lts-announce/2024/12/msg00026.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FJD4Q4AJSGE5UIJI7OUYZY4HGGCVYQNI/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LAR54OV6EHA56B4XJF6RNPQ4HJ2ITU66/

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