CVE-2025-62727Public exploitNetwork attack vector

CPU exhaustion via quadratic Range merging

Published Oct 28, 2025 · Updated Oct 28, 2025

Denial of service in Kludex Starlette 0.39.0 through 0.49.0 allows remote attackers to exhaust CPU via a crafted HTTP Range header. FileResponse._parse_range_header scans accumulated results while merging numerous disjoint ranges, producing quadratic processing time. Exposure requires an endpoint using FileResponse or StaticFiles; one unauthenticated request can delay service without reading or altering data.

CVSS severity7.5
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in Kludex Starlette 0.39.0 through 0.49.0 allows remote attackers to exhaust CPU via a crafted HTTP Range header. FileResponse._parse_range_header scans accumulated results while merging numerous disjoint ranges, producing quadratic processing time. Exposure requires an endpoint using FileResponse or StaticFiles; one unauthenticated request can delay service without reading or altering data.

The record

CVE
CVE-2025-62727
Published
Oct 28, 2025
Updated
Oct 28, 2025
Vendor
Kludex
Product
Starlette
Classifications
CWE-407, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 28, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 28, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.49.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kludex · Starletteversion=< 0.49.1

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-407Inefficient Algorithmic Complexity
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo