How severe is CVE-2026-54283?

CVE-2026-54283 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-54283 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-54283?

CVE-2026-54283 affects Encode Starlette. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-54283?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-54283 have an EU (EUVD) identifier?

Yes. CVE-2026-54283 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38319.

When was CVE-2026-54283 published?

CVE-2026-54283 was published on 2026-06-22 and last updated on 2026-06-26.

CVE-2026-54283

CVE-2026-54283 is a high-severity vulnerability in Encode Starlette with a CVSS 3.x base score of 7.5. 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-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-38319
Weakness: CWE-770
Affected product: Encode Starlette
Published: 2026-06-22
Last modified: 2026-06-26

Description

Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1.

Frequently asked questions

What is CVE-2026-54283?: Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1.
How severe is CVE-2026-54283?: CVE-2026-54283 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-54283 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-54283?: CVE-2026-54283 affects Encode Starlette. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-54283?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-54283 have an EU (EUVD) identifier?: Yes. CVE-2026-54283 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38319.
When was CVE-2026-54283 published?: CVE-2026-54283 was published on 2026-06-22 and last updated on 2026-06-26.

References

https://github.com/Kludex/starlette/security/advisories/GHSA-82w8-qh3p-5jfq

Affected products (1)

cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:*

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