CVE-2022-26981 – CVE-2022-26981 is a buffer overflow vulnerabili... (How to Fix)

Q: What is the severity of CVE-2022-26981?

CVE-2022-26981 has a CVSS score of 7.8 (HIGH). CVE-2022-26981 is a buffer overflow vulnerability in Liblouis's compilePassOpcode function that can be triggered when processing translation tables. This allows attackers to execute arbitrary code or cause denial of service. Affected users include anyone using Liblouis for braille translation, particularly in accessibility tools and document processing systems.

📋 TL;DR

CVE-2022-26981 is a buffer overflow vulnerability in Liblouis's compilePassOpcode function that can be triggered when processing translation tables. This allows attackers to execute arbitrary code or cause denial of service. Affected users include anyone using Liblouis for braille translation, particularly in accessibility tools and document processing systems.

💻 Affected Systems

Products:

Liblouis

Versions: All versions through 3.21.0

Operating Systems: Linux, Windows, macOS, BSD

Default Config Vulnerable: ⚠️ Yes

Notes: Vulnerability is in the core library and affects all applications using Liblouis for braille translation.

📦 What is this software?

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, or ransomware deployment.

🟠

Likely Case

Denial of service causing application crashes and disruption of braille translation services.

🟢

If Mitigated

Limited impact with proper input validation and memory protections in place.

🌐 Internet-Facing: MEDIUM - Requires specific input to lou_checktable tool or processing of malicious translation tables.

🏢 Internal Only: MEDIUM - Similar risk profile but limited to internal users who can supply translation tables.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires crafting malicious translation tables and getting them processed through vulnerable functions.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 3.22.0 and later

Vendor Advisory: https://github.com/liblouis/liblouis/issues/1171

Restart Required: Yes

Instructions:

1. Download Liblouis 3.22.0 or later from official repository. 2. Compile and install following standard build procedures. 3. Restart all applications using Liblouis.

🔧 Temporary Workarounds

Disable lou_checktable tool

linux

Remove or restrict access to the vulnerable lou_checktable utility

sudo rm /usr/bin/lou_checktable
sudo chmod 000 /usr/bin/lou_checktable

Input validation for translation tables

all

Implement strict validation of translation table files before processing

🧯 If You Can't Patch

Implement strict access controls on who can supply translation tables
Run Liblouis in sandboxed/containerized environments with limited privileges

🔍 How to Verify

Check if Vulnerable:

Check Liblouis version: lou_checktable --version or check installed package version

Check Version:

lou_checktable --version 2>/dev/null || lou_translate --version 2>/dev/null || dpkg -l liblouis* 2>/dev/null || rpm -qa | grep liblouis

Verify Fix Applied:

Verify version is 3.22.0 or later and test with known safe translation tables

📡 Detection & Monitoring

Log Indicators:

Segmentation faults in Liblouis processes
Abnormal termination of braille translation services
Large or malformed translation table processing

Network Indicators:

Unusual file transfers of translation table files
Network connections from braille translation services to unexpected destinations

SIEM Query:

process_name:"lou_checktable" AND (event_type:"crash" OR exit_code:139)

📊 Metadata

CVE ID: CVE-2022-26981

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-120

Published: March 13, 2022

Last Updated: November 21, 2024

🔗 References

http://seclists.org/fulldisclosure/2022/Jul/12 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2022/Jul/15 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2022/Jul/16 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2022/Jul/18 Mailing List,Third Party Advisory
https://github.com/liblouis/liblouis/issues/1171 Exploit,Issue Tracking,Patch,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CFD2KIHESDUCNWTEW3USFB5GKTWT624L/
https://security.gentoo.org/glsa/202301-06 Third Party Advisory
https://support.apple.com/kb/HT213340 Third Party Advisory
https://support.apple.com/kb/HT213342 Third Party Advisory
https://support.apple.com/kb/HT213345 Third Party Advisory
https://support.apple.com/kb/HT213346 Third Party Advisory
http://seclists.org/fulldisclosure/2022/Jul/12 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2022/Jul/15 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2022/Jul/16 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2022/Jul/18 Mailing List,Third Party Advisory
https://github.com/liblouis/liblouis/issues/1171 Exploit,Issue Tracking,Patch,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CFD2KIHESDUCNWTEW3USFB5GKTWT624L/
https://security.gentoo.org/glsa/202301-06 Third Party Advisory
https://support.apple.com/kb/HT213340 Third Party Advisory
https://support.apple.com/kb/HT213342 Third Party Advisory
https://support.apple.com/kb/HT213345 Third Party Advisory
https://support.apple.com/kb/HT213346 Third Party Advisory

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