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CVE Record

CVE-2018-9230: In OpenResty through 1.13.6.1, URI parameters are obtained using the ngx.req.get_uri_args and ngx.req.get_p...

In OpenResty through 1.13.6.1, URI parameters are obtained using the ngx.req.get_uri_args and ngx.req.get_post_args functions that ignore parameters beyond the hundredth one, which might allow remote attackers to bypass intended access restrictions or interfere with certain Web Application Firewall (ngx_lua_waf or X-WAF) products. NOTE: the vendor has reported that 100 parameters is an intentional default setting, but is adjustable within the API. The vendor's position is that a security-relevant misuse of the API by a WAF product is a vulnerability in the WAF product, not a vulnerability in OpenResty

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This CVE concerns a default OpenResty Lua API behavior: request argument readers may ignore parameters beyond the 100th item. If a WAF or access-control rule relies on those functions without adjusting the limit, some parameters may escape inspection. The vendor states this is an intentional adjustable default, not an OpenResty flaw itself.

Executive priority

Prioritize a focused review if OpenResty or Lua-based WAF controls protect sensitive routes. Business urgency is lower where OpenResty is absent or request parameters are not used for access control. Do not assume patch-only remediation; the bundle frames this as API misuse risk.

Technical view

OpenResty through 1.13.6.1 is described as exposing ngx.req.get_uri_args and ngx.req.get_post_args defaults that return only the first 100 arguments. Security impact depends on downstream Lua WAF or application logic treating that parsed set as complete. The CVE notes possible bypass of intended restrictions or interference with ngx_lua_waf or X-WAF products.

Likely exposure

Exposure is most likely in OpenResty or nginx Lua deployments where Lua code, ngx_lua_waf, X-WAF, or custom middleware makes security decisions from default argument parsing. The bundle does not identify affected CPEs, package ranges beyond OpenResty through 1.13.6.1, or specific patched WAF products.

Exploitation context

The source bundle does not show CISA KEV listing, active exploitation, or reliable public exploitation status. The issue is conceptually simple but impact is configuration and implementation dependent. Treat it as a validation item for OpenResty-backed WAF and access-control paths, not as a confirmed internet-wide emergency.

Researcher notes

Key uncertainty is attribution of vulnerability. The CVE describes OpenResty behavior, while the vendor position says the 100-parameter default is intentional and adjustable, making security-relevant misuse a WAF or application issue. Validate actual parser limits and decision points before rating internal severity.

Mitigation direction

  • Inventory OpenResty/nginx Lua apps and WAFs using ngx.req.get_uri_args or get_post_args.
  • Configure explicit argument limits appropriate for security inspection, following OpenResty API or vendor guidance.
  • Review ngx_lua_waf or X-WAF deployments for rule bypass assumptions around parameter parsing.
  • Reject abnormal parameter counts at the edge where business-safe and operationally tested.
  • Monitor vendor advisories for affected WAF products; sources do not name a universal OpenResty patch.

Validation and detection

  • Confirm deployed OpenResty versions and Lua modules handling URI or POST arguments.
  • Inspect code for get_uri_args/get_post_args calls using default limits in security decisions.
  • Test defensive controls with benign high-parameter requests in a controlled environment.
  • Verify logs and WAF decisions account for parameters beyond normal business limits.
  • Document whether exposure depends on WAF behavior, application logic, or both.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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0CVSS vectors
0Timeline events
0ADP providers
3Source links

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Affected products

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n/an/an/aListed
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