CVE-2026-53540
CVE-2026-53540 is a low-severity vulnerability in Fastapiexpert Python-multipart with a CVSS 3.x base score of 3.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1284.
Key facts
- Severity: Low (CVSS 3.x base score 3.7)
- EPSS exploit prediction: 0% (12th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-38325
- Weakness: CWE-1284
- Affected product: Fastapiexpert Python-multipart
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2026-53540?
- 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.
- How severe is CVE-2026-53540?
- CVE-2026-53540 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
- Is CVE-2026-53540 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-53540?
- CVE-2026-53540 affects Fastapiexpert Python-multipart. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-53540?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-53540 have an EU (EUVD) identifier?
- Yes. CVE-2026-53540 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38325.
- When was CVE-2026-53540 published?
- CVE-2026-53540 was published on 2026-06-22 and last updated on 2026-06-26.
References
Affected products (1)
- cpe:2.3:a:fastapiexpert:python-multipart:*:*:*:*:*:python:*:*
More vulnerabilities in Fastapiexpert Python-multipart
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- CVE-2024-24762 — High (CVSS 7.5): `python-multipart` is a streaming multipart parser for Python. When using form data, `python-multipart` uses a Regular…
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