CVE-2026-56814 elixir-plug CVE debrief

Who should care

Any application using Plug.Parsers with the :multipart parser is affected. No authentication is required, only reachability of a multipart endpoint over HTTP. The vulnerability has a CVSS score of 6.9 and a severity of MEDIUM, indicating a medium priority for applications using Plug.Parsers with the :multipart parser.

Technical summary

The Plug.Parsers.MULTIPART parser charges the :length limit only for part body bytes; part header bytes are never counted, and a part with an empty body costs zero. An attacker can send a single request composed of many empty-body file parts, creating one temporary file per part, leading to inode and disk exhaustion and unbounded memory growth. The vulnerability affects plug versions from 1.4.0 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.0 before 1.19.5, and from 1.20.0 before 1.20.3.

Defensive priority

High priority for applications using Plug.Parsers with the :multipart parser due to the potential for denial of service and medium severity.

Recommended defensive actions

• Review and update Plug.Parsers.MULTIPART to version 1.16.6 or later
• Implement compensating controls to limit the number of temporary files created
• Monitor for suspicious activity and inode exhaustion
• Consider using alternative multipart parsers
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record was published on 2026-07-10T12:17:24.837Z and has not been modified since then. The NVD entry is currently Received. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the official advisory. The parser's :length budget is not enforced against all consumed resources, which allows an unauthenticated remote attacker to cause denial of service. Evidence limits suggest that an attacker can send a single request composed of many empty-body file parts, leading to inode and disk exhaustion and unbounded memory growth.

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.