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Resource Allocation Without LimitsWeakness · CWE-770

CVE-2026-42561

HIGH · 7.5 CVSS v3.1 Developing Published 2026-05-13
No fix yet
No fix has been published. The vendor has not shipped a fixed release or patch. You remain exposed.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.27, python-multipart has a denial of service vulnerability in multipart part header parsing. When parsing multipart/form-data, MultipartParser previously had no limit on the number of part headers or the size of an individual part header. An attacker could send a request with either many repeated headers without terminating the header block or a single very large header value, causing excessive CPU work before request rejection or completion. This vulnerability is fixed in 0.0.27.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-08-12.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Recommended fix High confidence

python-multipart version 0.0.27 or later

  1. Identify the current version of python-multipart in your environment by running: pip show python-multipart or checking your requirements.txt/poetry.lock file
  2. Upgrade python-multipart to version 0.0.27 or later using: pip install python-multipart>=0.0.27
  3. Verify the upgrade was successful by running: pip show python-multipart
  4. If you maintain an application that depends on python-multipart, run your test suite to ensure the upgrade does not break functionality
  5. Update your dependency lock file (requirements.txt, poetry.lock, Pipfile.lock, etc.) to lock the new version
Caveat Review release notes for 0.0.27 and subsequent versions for any API changes; minor version upgrades typically have low breaking change risk but test thoroughly

Generated from the published advisory — verify against the referenced sources before acting.

No vendor fix exists The vendor has not published a patch for this.

There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42561 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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