CVE-2026-54283: Starlette is a lightweight ASGI framework/toolkit

Q: How do I fix CVE-2026-54283?

starlette: upgrade to 1.3.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-54283 being exploited?

CVE-2026-54283 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-54283 affect?

CVE-2026-54283 affects starlette. Severity is high (CVSS 7.5). 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 sil

Q: How urgent is CVE-2026-54283?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2026-54283 is a high-severity flaw (CVSS 7.5) affecting starlette. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 appl

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-06-22
Last modified	2026-10-25

Publisher (CNA): GitHub, Inc. · Vendor: encode

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-22 18:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

encode starlette UPGRADE

Affected: >= 0.4.1 and < 1.3.1

Fixed in: 1.3.1

Safe to downgrade to: a release before 0.4.1

1. Check installed version

pip show starlette

2. UPGRADE to 1.3.1

pip install --upgrade "starlette>=1.3.1"

3. If no update is available yet, DOWNGRADE to a release before 0.4.1

pip index versions starlette pip install "starlette<0.4.1"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-54283?

starlette: upgrade to 1.3.1. Exact commands for each OS are on this page.

Is CVE-2026-54283 being exploited?

CVE-2026-54283 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-54283 affect?

CVE-2026-54283 affects starlette. Severity is high (CVSS 7.5). 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 sil

How urgent is CVE-2026-54283?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-48817 MEDIUM 5.3 UPGRADE Starlette is a lightweight ASGI framework/toolkit
CVE-2026-54282 LOW 3.7 UPGRADE Starlette is a lightweight ASGI framework/toolkit
CVE-2026-48710 MEDIUM 6.5 EXPLOITED UPGRADE UPGRADE Kludex Starlette HTTP Request/Response Smuggling Vulnerability

References

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