{"answers":{"affected":"3 open source packages ship an affected version, including python-multipart. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-53539 in the wild and no public exploit code.","fix":"Upgrade python-multipart to 0.0.30 or later.","what":"CVE-2026-53539 is a high-severity denial of service vulnerability in Kludex python-multipart, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-53539 and fix it if it is affected.\n\nWhat it is: CVE-2026-53539 is a high-severity denial of service vulnerability in Kludex python-multipart, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-53539 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- python-multipart (PyPI): affected all versions; fixed in 0.0.30\n- python-multipart (PyPI): affected all versions; fixed in 0.0.30\n- python-multipart (PyPI): affected all versions; fixed in 0.0.30\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-53539/ (Markdown: https://insights.sbomify.com/CVE-2026-53539/index.md)","id":"CVE-2026-53539","markdown":"https://insights.sbomify.com/CVE-2026-53539/index.md","name":"CVE-2026-53539","record":{"aliases":["CLEANSTART-2026-EB34508","CLEANSTART-2026-SR16406","DEBIAN-CVE-2026-53539","ECHO-1942-6e43-27d8","GHSA-5rvq-cxj2-64vf","MINI-2r4m-69f3-x4pm","MINI-42rh-hcq3-w938","MINI-5xcf-v2vx-q275","MINI-9f6c-xgfg-g7f7","MINI-9g7m-mvqj-vv25","MINI-9rp5-cv62-7m5g","MINI-cvf4-prjx-w93j","MINI-fqx4-6prh-77hw","MINI-hx7x-xj5j-3xr5","MINI-jpp3-qhg2-hhrq","MINI-m74v-grjf-47q9","MINI-q2r5-mcgf-r6rv","MINI-r2qj-36r2-gj58","MINI-rcmw-x7mj-7cwp","MINI-wp85-p8hh-c55m","MINI-x6w7-9mg7-5xxx","PYSEC-2026-3036","ROOT-APP-PYPI-CVE-2026-53539","UBUNTU-CVE-2026-53539"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["denial_of_service"],"network_reachable":"yes","non_default_config":false,"product_category":"Python multipart parser","requires_auth":"none","summary":"An attacker can cause CPU exhaustion and denial of service by submitting crafted querystring bodies with semicolon separators to applications using Python-Multipart.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"python-multipart","vendor":"fastapiexpert"}],"cvss":{"score":7.5,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-407","name":"Inefficient Algorithmic Complexity"},{"id":"CWE-400","name":"Uncontrolled Resource Consumption"}],"description":"Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.30, when parsing application/x-www-form-urlencoded bodies, QuerystringParser located the field separator with a two step lookup: it first scanned the entire remaining buffer for \u0026, and only when no \u0026 existed anywhere ahead did it fall back to scanning for ;. For a body that uses ; as the separator and contains no \u0026, every field iteration performed a full failed \u0026 scan over the entire remaining buffer before locating the nearby ;. With N semicolon separated fields in a chunk of size B, this yields O(B^2) byte comparisons per chunk. An attacker can submit a small crafted body of the form a;a;a;... and cause the parser to spend seconds of CPU per request. A handful of concurrent requests can exhaust worker processes. This vulnerability is fixed in 0.0.30.","ecosystems":["PyPI"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"Python-Multipart: Quadratic-time querystring parsing with semicolon separators causes CPU denial of service","id":"CVE-2026-53539","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"PyPI","product":null,"products":[],"type":"denial_of_service","year":"2026"},"n_packages":3,"n_references":1,"next":{"headline":"Python-Multipart: Negative Content-Length in parse_form buffers the entire body in memory","id":"CVE-2026-53540"},"packages":[{"ecosystem":"PyPI","fixed":["0.0.30"],"introduced":["0"],"last_affected":[],"package":"python-multipart","purl":null,"source":"GHSA-5rvq-cxj2-64vf"},{"ecosystem":"PyPI","fixed":["0.0.30"],"introduced":["0"],"last_affected":[],"package":"python-multipart","purl":"pkg:pypi/python-multipart","source":"GHSA-5rvq-cxj2-64vf"},{"ecosystem":"PyPI","fixed":["0.0.30"],"introduced":["0"],"last_affected":[],"package":"python-multipart","purl":"pkg:pypi/python-multipart","source":"PYSEC-2026-3036"}],"prev":{"headline":"Python-Multipart: Semicolon treated as querystring field separator enables parameter smuggling","id":"CVE-2026-53538"},"products":["python-multipart"],"published":"2026-06-22","related":[{"cvss_score":8.6,"headline":"Python-Multipart has Arbitrary File Write via Non-Default Configuration","id":"CVE-2026-24486","kev_date_added":null,"published":"2026-01-27"},{"cvss_score":7.5,"headline":"python-multipart vulnerable to content-type header Regular expression Denial of Service","id":"CVE-2024-24762","kev_date_added":null,"published":"2024-02-05"},{"cvss_score":5.3,"headline":"Python-Multipart affected by Denial of Service via large multipart preamble or epilogue data","id":"CVE-2026-40347","kev_date_added":null,"published":"2026-04-17"},{"cvss_score":3.7,"headline":"Python-Multipart: Content-Disposition parameter smuggling via RFC 2231/5987 extended parameters","id":"CVE-2026-53537","kev_date_added":null,"published":"2026-06-22"},{"cvss_score":3.7,"headline":"Python-Multipart: Semicolon treated as querystring field separator enables parameter smuggling","id":"CVE-2026-53538","kev_date_added":null,"published":"2026-06-22"},{"cvss_score":3.7,"headline":"Python-Multipart: Negative Content-Length in parse_form buffers the entire body in memory","id":"CVE-2026-53540","kev_date_added":null,"published":"2026-06-22"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"PyPA Advisory Database","prefix":"PYSEC"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"yes","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-06-23","vendors":["Kludex"]},"summary":"An attacker can cause CPU exhaustion and denial of service by submitting crafted querystring bodies with semicolon separators to applications using Python-Multipart.","url":"https://insights.sbomify.com/CVE-2026-53539/"}