Atomicorp WAF Rule 345271

Rule Summary

• Rule ID: 345271
• Status: Active
• Alert message: Atomicorp.com WAF Rules: CVE-2026-9256 tripwire: oversized total REQUEST_URI length
• Observed CWEs: CWE-918 (1)
• Revision: 1
• Rule severity: Notice
• Phase: 1 (request headers)
• Request surfaces: Request URI
• Rule action: pass
• Public tags: CVE-2026-9256, application-multi, attack-protocol, nginx
• Logging: log

Description

This rule detects behavior identified by its current alert as “CVE-2026-9256 tripwire: oversized total REQUEST_URI length” in the request URI. It evaluates during the request headers phase and records the match without a disruptive action.

CVEs Referenced by This Rule

The current ModSecurity rule metadata explicitly names the following CVEs. These references explain the rule author’s association; they do not claim that the rule is limited to these vulnerabilities or that this is an exhaustive coverage list.

CVE-2026-9256

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

• Association: The rule references CVE-2026-9256 in its alert message and tag.
• CVE Record (opens in a new tab)
• NVD (opens in a new tab)

Selected Related CVEs

This is a selected list of documented research observations, not an exhaustive coverage matrix. Absence of a CVE does not imply absence of protection.

Observed CWEs

These CWEs are recorded on published CVEs in the selected observations associated with this rule. They are observational relationships, not a claim that the rule universally blocks every vulnerability assigned to a CWE.