CVE-2026-53540

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{"bugzilla": {"description": "python-multipart: Python-Multipart: Negative Content-Length in parse_form buffers the entire body in memory", "id": "2491443", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2491443"}, "csaw": false, "cvss3": {"cvss3_base_score": "3.7", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L", "status": "draft"}, "cwe": "CWE-400", "details": ["Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.31, parse_form() did not validate the Content-Length header before using it to bound its chunked read of the request body. A negative Content-Length turned the bounded read into a read-until-EOF, so the entire body was loaded into memory in a single read instead of in fixed-size chunks. This vulnerability is fixed in 0.0.31."], "mitigation": {"lang": "en:us", "value": "Upgrade python-multipart to version 0.0.31 or later, which rejects a negative Content-Length with a ValueError before reading the stream. As a workaround, configure the HTTP stack or reverse proxy to reject or normalize negative Content-Length headers before they reach the application layer."}, "name": "CVE-2026-53540", "package_state": [{"cpe": "cpe:/a:redhat:exploit_intelligence:0", "fix_state": "Fix deferred", "package_name": "exploit-intelligence-tech-preview/vulnerability-analysis-rhel9", "product_name": "Exploit Intelligence"}, {"cpe": "cpe:/a:redhat:migration_toolkit_applications:8", "fix_state": "Fix deferred", "package_name": "mta/mta-solution-server-rhel9", "product_name": "Migration Toolkit for Applications 8"}, {"cpe": "cpe:/a:redhat:openshift_lightspeed", "fix_state": "Not affected", "package_name": "openshift-lightspeed/lightspeed-agentic-sandbox-rhel9", "product_name": "OpenShift Lightspeed"}, {"cpe": "cpe:/a:redhat:openshift_lightspeed", "fix_state": "Fix deferred", "package_name": "openshift-lightspeed/lightspeed-ocp-rag-rhel9", "product_name": "OpenShift Lightspeed"}, {"cpe": 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"cpe:/a:redhat:satellite:6", "fix_state": "Fix deferred", "package_name": "satellite/iop-host-inventory-rhel9", "product_name": "Red Hat Satellite 6"}, {"cpe": "cpe:/a:redhat:satellite:6", "fix_state": "Fix deferred", "package_name": "satellite/iop-vmaas-rhel9", "product_name": "Red Hat Satellite 6"}, {"cpe": "cpe:/a:redhat:satellite:6", "fix_state": "Fix deferred", "package_name": "satellite/iop-vulnerability-engine-rhel9", "product_name": "Red Hat Satellite 6"}], "public_date": "2026-06-22T16:58:54Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-53540\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-53540\nhttps://github.com/Kludex/python-multipart/security/advisories/GHSA-v9pg-7xvm-68hf"], "statement": "A flaw was found in python-multipart where parse_form() did not validate the Content-Length header before using it to bound its chunked read of the request body. A negative Content-Length turns the bounded read into a read-until-EOF, loading the entire body into memory in a single operation instead of in fixed-size chunks. The realistic exposure is limited to bespoke WSGI or http.server handlers that forward raw client headers directly into parse_form(). Common frameworks such as Starlette and FastAPI do not call parse_form() directly and are not affected by this specific code path.", "threat_severity": "Low"}

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