CVE-2026-107834 corazawaf CVE debrief

Who should care

Defenders responsible for OWASP Coraza WAF deployments should assess exposure and apply the patch to prevent potential resource exhaustion attacks. This includes reviewing system configurations, monitoring for unusual activity, and implementing compensating controls where necessary. Security teams and operators managing OWASP Coraza WAF instances should prioritize verifying exposure and applying the patch to mitigate potential operational impacts.

Why it matters

Defenders should prioritize verifying exposure and applying the patch to prevent potential resource exhaustion attacks in OWASP Coraza WAF versions 3.0.0 through 3.7.0.

• Potential resource exhaustion leading to os.CreateTemp failures
• MULTIPART_STRICT_ERROR responses blocking legitimate uploads
• Process-wide inability to open files or sockets

Technical summary

The multipart loop in internal/bodyprocessors/multipart.go executes defer temp.Close() for every uploaded file part, keeping each temporary-file descriptor open until the complete request returns. An unauthenticated attacker can submit a multipart body containing many minimal file parts and exhaust the process file-descriptor table within the request-body size limit. This can lead to os.CreateTemp failures, MULTIPART_STRICT_ERROR responses, blocked legitimate uploads, and process-wide inability to open files or sockets. The vulnerability is caused by the improper handling of temporary file descriptors in the multipart body processor.

Defensive priority

Defenders should prioritize verifying exposure and applying the patch to prevent potential resource exhaustion attacks.

Recommended defensive actions

• Verify if the system uses OWASP Coraza WAF versions 3.0.0 through 3.7.0 and apply patch version 3.8.0
• Monitor for unusual increases in file descriptor usage or MULTIPART_STRICT_ERROR responses
• Implement compensating controls to limit the impact of potential resource exhaustion attacks
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by the multipart loop in internal/bodyprocessors/multipart.go executing defer temp.Close() for every uploaded file part, keeping each temporary-file descriptor open until the complete request returns.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.