CVE-2014-9765

What it actually does

Buffer overflow in main_get_appheader allows remote code execution when processing a crafted input file.

Why it matters to the business

Systems that decompress or patch files with xdelta3 face risk of full host compromise; the flaw affects multiple Linux distributions and the upstream tool but shows no active exploitation campaigns.

How an attack unfolds

An attacker creates a malicious xdelta patch file that triggers the overflow in main_get_appheader; when a user or automated process opens the file with a vulnerable xdelta3 binary, the overflow overwrites memory and executes attacker-supplied code.

How to fix it

Upgrade xdelta3 to version 3.0.9 or later on all affected systems; rebuild any custom packages that embed the vulnerable code.

How to confirm the fix worked

Confirm the installed xdelta3 binary reports version 3.0.9 or higher; re-test with known-good and known-bad patch files to verify the overflow is no longer reachable.

Typical attack path

1. Attacker crafts a malicious input file targeting main_get_appheader
2. Victim or automated workflow opens the file with vulnerable xdelta3
3. Buffer overflow occurs and attacker payload gains code execution
4. Attacker establishes persistence or exfiltrates data on the compromised host

How to detect it

Search process execution logs and file-access telemetry for xdelta3 invocations on unexpected or untrusted patch files; monitor for segmentation faults or abnormal memory usage during xdelta3 runs.

• xdelta3-main.h
• main_get_appheader

What your security team should do

• Inventory all hosts and containers running xdelta3 and schedule immediate upgrades
• Block untrusted xdelta patch files at mail gateways and file-transfer systems until patches are applied
• Add xdelta3 version checks to vulnerability scanners and CI pipelines