CVE-2026-26157
📋 TL;DR
A path traversal vulnerability in BusyBox's archive extraction utilities allows attackers to create malicious archives that, when extracted under specific conditions, can write files outside the intended directory. This can lead to arbitrary file overwrite and potential code execution by modifying sensitive system files. Affects systems using BusyBox's archive tools (like tar) to extract untrusted archives.
💻 Affected Systems
- BusyBox
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution via overwriting critical system files (like /etc/passwd, init scripts) or privilege escalation if extraction runs with elevated privileges.
Likely Case
Local file corruption or denial of service by overwriting configuration files, potentially leading to system instability.
If Mitigated
Limited impact if extraction runs in isolated containers, with minimal privileges, and on non-critical filesystems.
🎯 Exploit Status
Exploitation depends on conditions like extraction directory permissions and user privileges; no public proof-of-concept confirmed as of now.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in BusyBox commit 3fb6b31c716669e12f75a2accd31bb7685b1a1cb; check distribution-specific patches (e.g., Red Hat advisories).
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2026-26157
Restart Required: No
Instructions:
1. Update BusyBox to a patched version from your distribution's repository. 2. For embedded systems, rebuild BusyBox with the fix or apply vendor patches. 3. Verify the fix by checking the version or commit hash.
🔧 Temporary Workarounds
Restrict archive extraction to trusted sources
allOnly extract archives from verified and trusted sources to prevent malicious input.
Run extraction in isolated environments
linuxUse containers or chroot jails with limited filesystem access when extracting untrusted archives.
docker run --rm -v /safe/dir:/extract busybox tar -xf archive.tar -C /extract
🧯 If You Can't Patch
- Monitor and audit archive extraction activities for unusual file writes outside intended directories.
- Implement strict file permissions and use least-privilege principles for processes that handle archive extraction.
🔍 How to Verify
Check if Vulnerable:
Check BusyBox version and compare with patched commit; if using a distribution, refer to its security advisory for vulnerable versions.Check Version:
busybox --help 2>&1 | head -1Verify Fix Applied:
Verify the BusyBox binary includes the fix commit 3fb6b31c716669e12f75a2accd31bb7685b1a1cb or that your distribution marks it as patched.📡 Detection & Monitoring
Log Indicators:
- Log entries showing archive extraction errors or unexpected file writes outside extraction directories.
- System logs indicating file modifications in sensitive paths (e.g., /etc) following extraction.
Network Indicators:
- Unusual network transfers of archive files to systems running BusyBox, especially from untrusted sources.
SIEM Query:
Example: search for 'tar' or 'busybox' process executions followed by file write events in directories like /etc or /root.