`CVE-2026-48710` Starlette

Affected software	Starlette
Severity	6.5 Medium CVSS 3.1 3 scores
Weakness	CWE-444
Published	26 May 2026
Updated	1 Oct 2026

Description

Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP Host request header was not validated before being used to reconstruct request.url. Because the routing algorithm relies on the raw HTTP path while request.url is rebuilt from the Host header, a malformed header could make request.url.path differ from the path that was actually requested. Middleware and endpoints that apply security restrictions based on request.url (rather than the raw scope path) could therefore be bypassed. Users should upgrade to a version greater than or equal to version 1.0.1, which validates the Host header against the grammar of RFC 9112 §3.2 / RFC 3986 §3.2.2 when constructing request.url and falls back to scope["server"] for malformed values.

CWE-1289

Exploitation status

Exploited

Confirmed real-world exploitation.

CISA KEV listed Confirmed exploitation in the wild. Added 2026-09-02 · remediation due 2026-09-16 · ransomware use: unknown
VulnCheck KEV listed Exploitation reported in the wild. 5 citations · 1 exploit · earliest 2026-05-26.
CISA Vulnrichment exploitation: active CISA records active exploitation. Automatable: yes, technical impact: partial.
Indexed PoC 6 indexed Published artifacts you can open, in GitHub PoC, Nuclei; first seen 2026-04-01.
EPSS 70% chance in 30 days A model's forecast, not a report of exploitation. Higher than 99% of all scored CVEs.

VulnCheck KEV

Exploitation evidence from VulnCheck Known Exploited Vulnerabilities (VulnCheck KEV), used under VulnCheck's community terms. View CVE-2026-48710 in VulnCheck (free account).

Evidence	Source	Detail	Date
Reported exploitation	euvd.enisa.europa.eu	/enisa/EUVD-2026-32016	2026-05-26
Reported exploitation	microsoft.com	/en-us/security/blog/2026/08/26/when-ai-infrastructure-becomes-target-securing-gateways-control-points	2026-08-26
Reported exploitation	wiz.io	/blog/ai-infrastructure-honeypot	2026-08-27
Reported exploitation	previdian.com	/CVE-2026-48710	2026-09-02
Reported exploitation	cisa.gov	/sites/default/files/feeds/known_exploited_vulnerabilities.json	2026-09-02
Exploit reference	VulnCheck XDB 9d8edc626108	Exploit type: initial-access	2026-08-11

Evidence

Source

Detail

Date

Reported exploitation

euvd.enisa.europa.eu

/enisa/EUVD-2026-32016

2026-05-26

Reported exploitation

microsoft.com

/en-us/security/blog/2026/08/26/when-ai-infrastructure-becomes-target-securing-gateways-control-points

2026-08-26

Reported exploitation

wiz.io

/blog/ai-infrastructure-honeypot

2026-08-27

Reported exploitation

previdian.com

/CVE-2026-48710

2026-09-02

Reported exploitation

cisa.gov

/sites/default/files/feeds/known_exploited_vulnerabilities.json

2026-09-02

Exploit reference

VulnCheck XDB 9d8edc626108

Exploit type: initial-access

2026-08-11

5 of these are GitHub repositories with fewer than 5 stars. They are listed for reference and don't count toward the exploitation status above.

Index	Artifact	Stars	First seen
GitHub PoC	Detect, assess, and respond to supply chain attacks across npm/yarn and Python (pip/poetry/uv). Claude Code skill + standalone scripts. Built during axios RAT (2026-03-31) and Starlette BadHost CVE-2026-48710 (2026-05-22).	3	2026-04-01
GitHub PoC	Detection scanner for CVE-2026-48710 - Host-header auth bypass in Starlette/FastAPI	1	2026-05-28
GitHub PoC	Starlette Host-Header URL Confusion Lab (X41-2026-002) - CVE-2026-48710	1	2026-05-27
GitHub PoC	CVE-2026-48710漏洞验证代码		2026-08-11
GitHub PoC	OXDEV-77637 repro fixture: uv workspace whose transitive CVE (starlette 0.25.0 / CVE-2026-48710) is dropped when the lean clone omits workspace-member pyproject.toml. Tag: repro-OXDEV-77637		2026-08-03
Nuclei	Starlette - Improper Validation of Unsafe Equivalence in Input

Waratek protection

Outside Waratek scope

A Java vulnerability, but not one Waratek protects. It affects only Java on a user's desktop (applets, Web Start, JavaFX, the installer), sits in a product the Waratek agent can't be installed into, or is in a package we don't expect in business applications. The decision below says which.

Protection none
Action not pursued none
Review automated Upstream data
Record active

Decided by	The only affected product being a sealed appliance image, where Java runs but no -javaagent can be attached
Finding	This CVE names only products the Waratek agent cannot be installed into (redhat/satellite). They ship as sealed appliance images or as native code with no application JVM, so there is no start-up line to add -javaagent to. The vulnerability may well be a Java one; it is permanently out of ARMR's reach rather than outside its subject.

Decided by

The only affected product being a sealed appliance image, where Java runs but no -javaagent can be attached

Finding

This CVE names only products the Waratek agent cannot be installed into (redhat/satellite). They ship as sealed appliance images or as native code with no application JVM, so there is no start-up line to add -javaagent to. The vulnerability may well be a Java one; it is permanently out of ARMR's reach rather than outside its subject.

CVSS

6.5 MEDIUM v3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N 3 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

Version Score Band Vector Assigner Type

CVSS 3.1 6.5 MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N security-advisories@github.com Secondary published

CVSS 3.1 6.5 MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N NVD Primary

CVSS 3.1 6.5 MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N redhat-SADP Secondary

Version	Score	Band	Vector	Assigner	Type
CVSS 3.1	6.5	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`	security-advisories@github.com	Secondary	published
CVSS 3.1	6.5	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`	NVD	Primary
CVSS 3.1	6.5	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`	redhat-SADP	Secondary

Affected software and releases

Products and versions

8 products, 12 version entries

Source	Vendor	Product	Scheme	Affected versions
nvd	encode	starlette	generic	≥ 0.8.3 and ＜ 1.0.1
nvd	redhat	ai inference server	generic	≥ 3.3.0 and ≤ 3.3.5
nvd	redhat	ansible automation platform	generic	2.6 · 2.7
nvd	redhat	enterprise linux ai	generic	3.0
nvd	redhat	migration toolkit for applications	generic	＜ 8.2.0
nvd	redhat	openshift ai	generic	≥ 3.3 and ＜ 3.3.5 · ≥ 3.4 and ＜ 3.4.2
nvd	redhat	openshift lightspeed	generic	any version
nvd	redhat	satellite	generic	6.17 · 6.18 · 6.19

Source

Vendor

Product

Scheme

Affected versions

nvd

encode

starlette

generic

≥ 0.8.3 and ＜ 1.0.1

nvd

redhat

ai inference server

generic

≥ 3.3.0 and ≤ 3.3.5

nvd

redhat

ansible automation platform

generic

2.6 · 2.7

nvd

redhat

enterprise linux ai

generic

3.0

nvd

redhat

migration toolkit for applications

generic

＜ 8.2.0

nvd

redhat

openshift ai

generic

≥ 3.3 and ＜ 3.3.5 · ≥ 3.4 and ＜ 3.4.2

nvd

redhat

openshift lightspeed

generic

any version

nvd

redhat

satellite

generic

6.17 · 6.18 · 6.19

References

URL	Tags
https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
https://badhost.org	Mitigation, Third Party Advisory
https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6	Patch
https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml	Third Party Advisory
https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette	Mitigation, Third Party Advisory
https://www.secwest.net/starlette	Exploit, Mitigation, Third Party Advisory
https://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette	Exploit, Mitigation, Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:22992	Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:22993	Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:23346	Third Party Advisory

URL

Timeline

Published	2026-05-26	By the CVE Program.
VulnCheck KEV: earliest evidence	2026-05-26	Date of the oldest evidence of exploitation in VulnCheck KEV's record. VulnCheck does not publish the date it listed the CVE.
Added to CISA KEV	2026-09-02	Listed in CISA's Known Exploited Vulnerabilities catalog.
VulnCheck KEV: latest evidence	2026-09-02	Date of the newest report, exploit reference or honeypot sighting in VulnCheck KEV's record.
NVD record modified	2026-10-01	NVD's own last-modified date for this record.

Published

2026-05-26

By the CVE Program.

VulnCheck KEV: earliest evidence

2026-05-26

Date of the oldest evidence of exploitation in VulnCheck KEV's record. VulnCheck does not publish the date it listed the CVE.

Added to CISA KEV

2026-09-02

Listed in CISA's Known Exploited Vulnerabilities catalog.

VulnCheck KEV: latest evidence

2026-09-02

Date of the newest report, exploit reference or honeypot sighting in VulnCheck KEV's record.

NVD record modified

2026-10-01

NVD's own last-modified date for this record.

How VRT decided (15 of 24 rules ran)

15 of 24 rules ran. The rest didn't run because an earlier rule had already settled the CVE.

# Rule Outcome Status Detail

identity: Does this identifier describe a vulnerability at all? the first rule that matches decides

1 rejected no match CVE Program withdrawal of this identifier

scope: Is it a vulnerability Waratek protects? the first rule that matches decides

2 armr-patch-file no match An ARMR patch file on disk for this CVE

3 armr-secure-rule-file no match An ARMR security-rule template on disk for this CVE

4 manual-classification no match A researcher's recorded decision for this specific CVE

5 manual classification no match Manual classification of this CVE in the legacy dataset

6 non-java-upstream no match A root cause in non-Java code: an OS kernel, a C library, or a bundled runtime

7 oracle-component no match The defect being in a component of a tracked product the agent does not reach: JavaFX, the Java SE installer, the JInitiator browser plug-in, the native WebLogic proxy plug-in, or a native part of Oracle Application Server or Collaboration Suite (HTTP Server, Web Cache, Internet Directory, mail and calendar servers). Oracle gives these no CPE of their own and names them only in the description.

8 java-client-side no match Oracle's own risk-matrix note saying the CVE is reached only through untrusted code in the Java sandbox (applets, Web Start) or only through a client installation of Java, so a server running its own trusted code is not exposed

9 osv-maven no match An OSV.dev record of this CVE affecting a package published to Maven Central. When every such package is one business applications do not use (Minecraft mods and launchers, Fastjson) and no tracked product is named by CPE, it settles the CVE as Outside Waratek scope instead

10 cna-maven-package no match An affected Maven artifact named by the CNA itself

11 known-cpe-product no match An NVD CPE naming a product ARMR tracks

12 cna-cpe-product no match A CPE the CNA published naming a tracked product. Oracle publishes these on advisory day, months before NVD.

13 oracle-advisory-family no match A tracked product family named in Oracle's own risk matrix. CPE cannot carry a suite name, only a module.

14 cna-named-product no match A tracked product named in words by the CVE's own CNA, on a record with no CPE yet. Apache and Eclipse publish these on advisory day, before NVD adds CPE data.

15 non-deployable-product decided it matched Outside Waratek scope Named products cannot host a Java agent: redhat/satellite

16 unmatched-product not reached No tracked product matched above, and none present at all

disposition: What do we do about one that is? every rule runs

17 patch-hint not reached A reference pointing at the upstream fix: a commit, a PR, a Red Hat bug

18 open-source-maven not reached The affected package being open source on Maven, so the fix can be read

19 poc-derivable not reached An indexed exploit clearing the evidence bar to reverse-engineer, where there is no source to read

20 no-exploit not reached Nothing to build a rule from yet: no published exploit, no CISA record of exploitation and no source-level change to read

21 secure-rule-match not reached A vulnerability class already blocked by an ARMR security rule

22 exploited-no-fix-or-poc not reached Somebody exploiting this CVE (a CISA or VulnCheck KEV listing, or a CISA verdict of active exploitation), with no fix, source code or PoC to build a rule from

23 below-action-threshold not reached Medium or Low severity, no CISA or VulnCheck KEV listing, no PoC clearing the evidence bar, no CISA verdict, no Oracle advisory

24 no-exploit-published not reached Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all

Products the scope rules checked

The products this CVE's record names, and whether VRT tracks each one. The scope rules decided on these.

Vendor Product Tracked CPE Source

encode starlette not tracked cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:*

redhat ai_inference_server not tracked cpe:2.3:a:redhat:ai_inference_server:*:*:*:*:*:*:*:*

redhat ansible_automation_platform not tracked cpe:2.3:a:redhat:ansible_automation_platform:2.6:-:*:*:*:*:*:*

redhat migration_toolkit_for_applications not tracked cpe:2.3:a:redhat:migration_toolkit_for_applications:*:*:*:*:*:*:*:*

redhat openshift_ai not tracked cpe:2.3:a:redhat:openshift_ai:*:*:*:*:*:*:*:*

redhat openshift_lightspeed not tracked cpe:2.3:a:redhat:openshift_lightspeed:-:*:*:*:*:*:*:*

redhat satellite not tracked cpe:2.3:a:redhat:satellite:6.17:*:*:*:*:*:*:*

redhat enterprise_linux_ai not tracked cpe:2.3:o:redhat:enterprise_linux_ai:3.0:*:*:*:*:*:*:*

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