CVE-2020-35502

What it actually does

Memory leaks triggered when Privoxy buffers responses and hits configured limits or exhausts available memory, resulting in process termination.

Why it matters to the business

Unexpected crashes of the proxy service can interrupt web filtering, privacy protections, and traffic routing for users or downstream applications until the service is restarted.

How an attack unfolds

An attacker sends a series of HTTP requests crafted to force Privoxy to buffer large responses until the internal buffer limit or system memory is exhausted, causing the daemon to crash and denying service to legitimate users.

How to fix it

Upgrade Privoxy to version 3.0.29 or later; if an upgrade is not immediately possible, restart the service on observed crashes and monitor memory usage to reduce downtime.

How to confirm the fix worked

Confirm the installed Privoxy version is 3.0.29 or newer; review process logs and memory statistics after sending test traffic that previously triggered buffering to verify stability.

Typical attack path

1. Identify a Privoxy instance reachable over the network
2. Send repeated or oversized HTTP responses that trigger buffering
3. Continue until buffer or memory limits are reached
4. Observe process crash and service unavailability

How to detect it

Search proxy and system logs for repeated Privoxy process terminations or out-of-memory events correlated with high-volume or large response traffic; no specific post-exploitation artifacts are known.

What your security team should do

• Prioritize upgrade to Privoxy 3.0.29 or newer on all instances
• Add monitoring for Privoxy process restarts and memory growth
• Review and tighten response buffering configuration where feasible