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CVE-2026-24486· NVD / CVE Program· CNA GitHub_M

Python-Multipart has Arbitrary File Write via Non-Default Configuration

Python-Multipart is a streaming multipart parser for Python. Prior to version 0.0.22, a Path Traversal vulnerability exists when using non-default configuration options `UPLOAD_DIR` and `UPLOAD_KEEP_FILENAME=True`. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename. Users should upgrade to version 0.0.22 to receive a patch or, as a workaround, avoid using `UPLOAD_KEEP_FILENAME=True` in project configurations.

HighCVSS 7.5 · v3.1—Proof of concept Fix available
Published
Jan 26, 2026
Updated
Sep 16, 2026
EPSS
2.2% · 82th percentile
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Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.5
CNA · GitHub_M
8.6
1.1 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

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Affected systems

VendorProduct
fastapiexpertpython-multipart

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fastapiexpert python-multipartbefore 0.0.22

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • Kludex python-multipart

    • < 0.0.22affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12python-multipartall versions—
Debian:13python-multipartbefore 0.0.20-1.1~deb13u10.0.20-1.1~deb13u1
Debian:14python-multipartbefore 0.0.20-1.10.0.20-1.1
openSUSE:Leap 15.6python-python-multipartbefore 0.0.9-150600.3.6.10.0.9-150600.3.6.1
openSUSE:Leap 16.0python-python-multipartbefore 0.0.20-160000.3.10.0.20-160000.3.1
PyPIpython-multipartbefore 0.0.220.0.22
SUSE:Linux Enterprise Server 16.0python-python-multipartbefore 0.0.20-160000.3.10.0.20-160000.3.1

Same product

fastapiexpert: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-53539Python-Multipart: Quadratic-time querystring parsing with semicolon separators causes CPU denial of service
    30Monitor
  • CVE-2024-24762python-multipart vulnerable to content-type header Regular expression Denial of Service
    30Monitor
  • CVE-2026-53537Python-Multipart: Content-Disposition parameter smuggling via RFC 2231/5987 extended parameters
    21Monitor
  • CVE-2026-40347Python-Multipart affected by Denial of Service via large multipart preamble or epilogue data
    21Monitor
  • CVE-2026-53540Python-Multipart: Negative Content-Length in parse_form buffers the entire body in memory
    14Monitor
  • CVE-2026-53538Python-Multipart: Semicolon treated as querystring field separator enables parameter smuggling
    14Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Kludex python-multipart0.0.22 · descriptionVendor (CNA)
debian:python-multipart0.0.20-1.1~deb13u1 · Debian:13Package registry (OSV)
opensuse:python-python-multipart0.0.9-150600.3.6.1 · openSUSE:Leap 15.6Package registry (OSV)
PyPI:python-multipart0.0.22Package registry (OSV)
suse:python-python-multipart0.0.20-160000.3.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entrywebapps2026-04-30

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+93 d
  3. TodayOct 11, 2026+257 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

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

nvd-primary

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

The bug in code

The whole CWE-22 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const file = path.join(ROOT, req.query.name);res.sendFile(file);

Fixed

ts
const file = path.resolve(ROOT, req.query.name);if (!file.startsWith(ROOT + path.sep)) {  return res.sendStatus(400);}res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records