Coraza: Silent argument drop at ArgumentLimit allows bypass of ARGS-targeted rules via parameter flooding

Why it is Amber

• CVSS 7.2 high
• Public exploit or proof of concept referenced
• Remotely exploitable without logging in
• On your watchlist: Go

Affected packages

References

• https://github.com/advisories/GHSA-6r3q-mjv7-xr8m
• https://github.com/corazawaf/coraza/security/advisories/GHSA-6r3q-mjv7-xr8m
• https://github.com/corazawaf/coraza/commit/146c2f79f39ad16f13787e7d67ad400f8d8cb9a3
• https://github.com/corazawaf/coraza/commit/814e1898e083d2ff2ceb644382d0da17e930f93f
• https://github.com/corazawaf/coraza/commit/b98359bb7e7606c95100dcc7ad490d2d624e6dea
• https://github.com/corazawaf/coraza/releases/tag/v3.8.1
• https://github.com/advisories/GHSA-6r3q-mjv7-xr8m

Original description

OWASP Coraza WAF is a golang modsecurity compatible web application firewall library. From 3.0.0 until 3.8.1, Coraza silently drops arguments after SecArgumentsLimit in internal/corazawaf/transaction.go, while internal/bodyprocessors/urlencoded.go writes ARGS_POST without enforcing the cap. The flaw is triggered when an unauthenticated attacker sends more arguments than SecArgumentsLimit or supplies bodies that expand beyond the configured argument and flattening budgets. An unauthenticated attacker can flood requests with arguments so excess values are silently omitted from ARGS, ARGS_GET, ARGS_NAMES, ARGS_GET_NAMES, ARGS_POST, or ARGS_PATH before security rules inspect them; affected urlencoded and JSON processing can also consume excessive memory. The omission can bypass WAF rules protecting the downstream application, and unbounded or amplified argument processing can cause memory consumption and service degradation. This issue is fixed in version 3.8.1.