CVE-2023-2603 – An integer overflow vulnerability in libcap's

Q: What is the severity of CVE-2023-2603?

CVE-2023-2603 has a CVSS score of 7.8 (HIGH). An integer overflow vulnerability in libcap's _libcap_strdup() function allows memory corruption when processing extremely large strings (close to 4GB). This affects any system using vulnerable versions of libcap, which is a Linux library for managing POSIX capabilities.

📋 TL;DR

An integer overflow vulnerability in libcap's _libcap_strdup() function allows memory corruption when processing extremely large strings (close to 4GB). This affects any system using vulnerable versions of libcap, which is a Linux library for managing POSIX capabilities.

💻 Affected Systems

Products:

libcap

Versions: Versions before 2.69

Operating Systems: Linux distributions using vulnerable libcap versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only exploitable if applications use libcap functions with attacker-controlled input strings approaching 4GB in size.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to full system compromise if an attacker can trigger the overflow through a vulnerable application.

🟠

Likely Case

Denial of service through application crashes or memory corruption in programs using libcap.

🟢

If Mitigated

Limited impact if systems are patched or don't process untrusted large strings through libcap functions.

🌐 Internet-Facing: MEDIUM - Requires specific conditions: internet-facing applications must use vulnerable libcap functions with attacker-controlled large inputs.

🏢 Internal Only: LOW - Most internal systems don't process 4GB strings through libcap in normal operations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires specific conditions: ability to provide ~4GB input strings to libcap functions and bypass memory protections like ASLR.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: libcap 2.69 and later

Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=2209113

Restart Required: Yes

Instructions:

1. Update libcap package using your distribution's package manager. 2. For Red Hat/Fedora: 'sudo dnf update libcap'. 3. For Debian/Ubuntu: 'sudo apt update && sudo apt install --only-upgrade libcap2'. 4. Restart affected services or reboot system.

🔧 Temporary Workarounds

Input validation

linux

Validate input string sizes in applications using libcap to prevent large inputs.

🧯 If You Can't Patch

Implement strict input validation in applications using libcap to reject strings larger than reasonable limits.
Use memory protection mechanisms like ASLR and stack canaries to make exploitation more difficult.

🔍 How to Verify

Check if Vulnerable:

Check libcap version: 'rpm -q libcap' (RHEL/Fedora) or 'dpkg -l libcap2' (Debian/Ubuntu). Versions before 2.69 are vulnerable.

Check Version:

rpm -q libcap || dpkg -l libcap2 | grep ^ii

Verify Fix Applied:

Verify libcap version is 2.69 or later using the same commands.

📡 Detection & Monitoring

Log Indicators:

Application crashes involving libcap functions
Memory corruption errors in system logs

Network Indicators:

Unusually large data transfers to applications using libcap

SIEM Query:

Process logs for applications using libcap with error messages containing 'segmentation fault', 'memory corruption', or similar terms.

📊 Metadata

CVE ID: CVE-2023-2603

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-190

Published: June 6, 2023

Last Updated: December 2, 2025

🔗 References

https://bugzilla.redhat.com/show_bug.cgi?id=2209113 Issue Tracking,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EZ57ICDLMVYEREXQGZWL4GWI7FRJCRQT/ Broken Link,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IPEGCFMCN5KGCFX5Y2VTKR732TTD4ADW/ Broken Link,Third Party Advisory
https://www.x41-dsec.de/static/reports/X41-libcap-Code-Review-2023-OSTIF-Final-Report.pdf Exploit,Technical Description
https://bugzilla.redhat.com/show_bug.cgi?id=2209113 Issue Tracking,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EZ57ICDLMVYEREXQGZWL4GWI7FRJCRQT/ Broken Link,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IPEGCFMCN5KGCFX5Y2VTKR732TTD4ADW/ Broken Link,Third Party Advisory
https://www.x41-dsec.de/static/reports/X41-libcap-Code-Review-2023-OSTIF-Final-Report.pdf Exploit,Technical Description

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