Security context
What an agent needs to avoid regressing past fixes and find the next vuln in this repo.
varnishcache/varnish-cache
master @ 0038dd1
121
Fixes
0
CVEs
HIGH
Peak severity
56.0%
Coverage
Highlights
Denial of Service: 76 prior fixes. Scrutinize any change in this area.
bin/varnishd/cache/cache_session.c: most-fixed (17 issues). Treat as high-risk during review.
35 high-severity fixes in this history; regressions here are high-impact.
Recurring patterns
The bug types that recur here, drawn from past fixes, not open vulnerabilities.
Denial of Service: Varnish is highly susceptible to stream-based starvation and rapid-reset DoS attacks in the HTTP/2 layer, where unconstrained frame generation or processing exhausts active thread pools and triggers panics. Implementing rate limits and sliding window budgets is crucial.
HTTP Request Smuggling: Improper validation of HTTP/2 pseudo-headers and field values during HPACK translation allows attackers to inject malicious headers, leading to request smuggling when proxied to HTTP/1.1 backends.
Auth Bypass: The VCL compiler's optimization passes are prone to logic bugs—specifically during ACL rule-folding and prefix matching—which can mistakenly collapse or misalign negated rules, letting unauthorized IPs bypass restrictions.