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Full vulnerability report · 2025
CVE-2025-62727High confidence

Starlette vulnerable to O(n^2) DoS via Range header merging in starlette.responses.FileResponse

Kludex · starlette

Official source article: GitHub GHSA-7F5H-V6XP-FCQ8 ↗. Check the applicable product and release in the original source.

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 4 Nov 2025

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.68% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Kludex starlette and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcestarletteVendor fix publishedDebian records a fixed source-package version for this release.0.46.1-3+deb13u1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcestarletteNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcestarletteVendor fix publishedDebian records a fixed source-package version for this release.0.50.0-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcestarletteVendor fix publishedDebian records a fixed source-package version for this release.0.50.0-1Debian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivestarletteUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Open-source package ranges2 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
PyPIstarletteECOSYSTEM: introduced 0.39.0; fixed 0.49.10.49.1OSV record ↗aggregator derived · 10 Sep 2026
pipstarlette>= 0.39.0, <= 0.49.00.49.1GitHub advisory ↗upstream repository advisory · 4 Nov 2025
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2025-62727 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitystarlette: Starlette DoS via Range header merging
17 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • openshift-lightspeed/lightspeed-ocp-rag-rhel9 as a component of OpenShift Lightspeed
  • openshift-lightspeed/lightspeed-service-api-rhel9 as a component of OpenShift Lightspeed
  • rhaiis/vllm-spyre-rhel9 as a component of Red Hat AI Inference Server
  • rhaiis/vllm-tpu-rhel9 as a component of Red Hat AI Inference Server
  • rhelai1/bootc-amd-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
  • rhelai1/bootc-aws-nvidia-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
  • rhelai1/bootc-azure-amd-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
  • rhelai1/bootc-azure-nvidia-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
  • rhelai1/bootc-gcp-nvidia-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
  • rhelai1/bootc-intel-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
  • rhelai1/bootc-nvidia-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
  • rhelai1/instructlab-amd-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI)
Summary
A denial of service vulnerability has been discovered in the python Starlette framework. an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This induces CPU exhaustion per request, causing a denial‑of‑service for endpoints serving files.
Remediation
For more information visit https://access.redhat.com/errata/RHSA-2025:23080
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-36555

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.

What

Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.

Why

An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Starlette is a lightweight ASGI framework/toolkit. Starting in version 0.39.0 and prior to version 0.49.1 , an unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial‑of‑service for endpoints serving files (e.g., StaticFiles or any use of FileResponse). This vulnerability is fixed in 0.49.1.

Why

An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
a network path → Inefficient Algorithmic Complexity → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-407 ↗

CWE-407: Inefficient Algorithmic Complexity. An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-407Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

Cyber Security Agency of Singapore · English · CSA-SB-20251029Security Bulletin 29 Oct 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 29 Oct 2025, published on 29 October 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0327Multiples vulnérabilités dans les produits IBM

ord?id=CVE-2025-53905 Référence CVE CVE-2025-53906 https://www.cve.org/CVERecord?id=CVE-2025-53906 Référence CVE CVE-2025-55173 https://www.cve.org/CVERecord?id=CVE-2025-55173 Référence CVE CVE-2025-57350 https://www.cve.org/CVERecord?id=CVE-2025-57350 Référence CVE CVE-2025-57352 https://www.cve.org/CVERecord?id=CVE-2025-57352 Référence CVE CVE-2025-57752 https://www.cve.org/CVERecord?id=CVE-2025-57752 Référence CVE CVE-2025-58457 https://www.cve.org/CVERecord?id=CVE-2025-58457 Référence CVE CVE-2025-59250 https://www.cve.org/CVERecord?id=CVE-2025-59250 Référence CVE CVE-2025-6176 https://www.cve.org/CVERecord?id=CVE-2025-6176 Référence CVE CVE-2025-62727 https://www.cve.org/CVERecord?id=CVE-2025-62727 Référence CVE CVE-2025-64775 https://www.cve.org/CVERecord?id=CVE-2025-64775 Référence CVE CVE-2025-6545 https://www.cve.org/CVERecord?id=CVE-2025-6545 Référence CVE CVE-2025-6547 https://www.cve.org/CVERecord?id=CVE-2025-6547 Référence CVE CVE-2025-66418 https://www.cve.org/CVERecord?id=CVE-2025-66418 Référence CVE CVE-2025-66453 https://www.cve.org/CVERecord?id=CVE-2025-66453 Référence CVE CVE-2025-66471 https://www.cve.org/CVERecord?id=CVE-2025-66471 Référence CVE CVE-2025-66675 https://www.cve.org/CVERecord?id=CVE-2025-66675 Référence CVE CVE-2025-68301 https://www.cve.org/CVERecord?id=CVE-

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0218Multiples vulnérabilités dans les produits VMware

ord?id=CVE-2025-61726 Référence CVE CVE-2025-61727 https://www.cve.org/CVERecord?id=CVE-2025-61727 Référence CVE CVE-2025-61728 https://www.cve.org/CVERecord?id=CVE-2025-61728 Référence CVE CVE-2025-61729 https://www.cve.org/CVERecord?id=CVE-2025-61729 Référence CVE CVE-2025-61730 https://www.cve.org/CVERecord?id=CVE-2025-61730 Référence CVE CVE-2025-61731 https://www.cve.org/CVERecord?id=CVE-2025-61731 Référence CVE CVE-2025-61732 https://www.cve.org/CVERecord?id=CVE-2025-61732 Référence CVE CVE-2025-6176 https://www.cve.org/CVERecord?id=CVE-2025-6176 Référence CVE CVE-2025-62408 https://www.cve.org/CVERecord?id=CVE-2025-62408 Référence CVE CVE-2025-62727 https://www.cve.org/CVERecord?id=CVE-2025-62727 Référence CVE CVE-2025-6395 https://www.cve.org/CVERecord?id=CVE-2025-6395 Référence CVE CVE-2025-64505 https://www.cve.org/CVERecord?id=CVE-2025-64505 Référence CVE CVE-2025-64506 https://www.cve.org/CVERecord?id=CVE-2025-64506 Référence CVE CVE-2025-64702 https://www.cve.org/CVERecord?id=CVE-2025-64702 Référence CVE CVE-2025-64718 https://www.cve.org/CVERecord?id=CVE-2025-64718 Référence CVE CVE-2025-64720 https://www.cve.org/CVERecord?id=CVE-2025-64720 Référence CVE CVE-2025-65018 https://www.cve.org/CVERecord?id=CVE-2025-65018 Référence CVE CVE-2025-66293 https://www.cve.org/CVERecord?id=CV

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-1138Multiples vulnérabilités dans VMware Tanzu Platform

d?id=CVE-2025-61723 Référence CVE CVE-2025-61724 https://www.cve.org/CVERecord?id=CVE-2025-61724 Référence CVE CVE-2025-61725 https://www.cve.org/CVERecord?id=CVE-2025-61725 Référence CVE CVE-2025-61727 https://www.cve.org/CVERecord?id=CVE-2025-61727 Référence CVE CVE-2025-61729 https://www.cve.org/CVERecord?id=CVE-2025-61729 Référence CVE CVE-2025-62164 https://www.cve.org/CVERecord?id=CVE-2025-62164 Référence CVE CVE-2025-62372 https://www.cve.org/CVERecord?id=CVE-2025-62372 Référence CVE CVE-2025-62426 https://www.cve.org/CVERecord?id=CVE-2025-62426 Référence CVE CVE-2025-62593 https://www.cve.org/CVERecord?id=CVE-2025-62593 Référence CVE CVE-2025-62727 https://www.cve.org/CVERecord?id=CVE-2025-62727 Référence CVE CVE-2025-66448 https://www.cve.org/CVERecord?id=CVE-2025-66448 Gestion détaillée du document le 26 décembre 2025 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défense et de la Sécurité Nationale / Agence nationale de la sécurité des systèmes d'information

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
Action
For more information visit https://access.redhat.com/errata/RHSA-2025:23080
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 28 Oct 2025 · Last source change 4 Nov 2025, 17:41 UTC · CWE-407 · Inefficient Algorithmic Complexity

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-36555
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    >= 0.39.0, < 0.49.1 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    >= 0.39.0, < 0.49.1 · Fixed: For more information visit https://access.redhat.com/errata/RHSA-2025:23080
    Red Hat Product Security ↗
  2. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-62727 · cve.blacktree.nl