What is CVE-2026-48710?

CVE-2026-48710 is Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks. The supplied enrichment data classifies it as Unclassified mapped to CWE-444 CWE-444; CWE-1289 CWE-1289.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Yes: CISA KEV signal present. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

Is there a public exploit?

35 public PoC repositories reported; 2 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-48710 using CVSS 6.5, EPSS 2%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

Workarounds are not confirmed from current sources. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

Publicly linked actor or ransomware signals in the supplied enrichment data: Awaken Likho (), Tortoiseshell (). Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Treat as emergency remediation because CISA KEV status is present. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

CISA KEVmediumpublic exploit

CVE-2026-48710

CVE-2026-48710 — Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks

Q: Is it in CISA KEV?

Yes. The supplied enrichment data lists CVE-2026-48710 in CISA KEV with required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

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.

Published May 26, 2026Updated Sep 2, 2026Sources: NVD, Kludex (CNA), CISA, FIRST EPSS, GitHub, GitHub Security Advisory, Red Hat (VEX), SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Confirmed

CISA KEV, listed Sep 2, 2026

EPSS

ahead of 80% of scored CVEs

Affects

Kludex

2 products listed

CVSS base

6.5

medium

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

Active

none · proof-of-concept · active

Automatable

can an attacker script all four kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

The vendor's own words where we have them.

Upgrade starlette to 1.0.1 or later (pip advisory GHSA-86qp-5c8j-p5mr).

CISA required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Federal deadline Sep 16, 2026 — in 11 days

Red Hat VEX · CVE-2026-48710

fixed92affected34not affected948

vendor_fix: For more information visit https://access.redhat.com/errata/RHSA-2026:30089

vendor_fix: For more information visit https://access.redhat.com/errata/RHSA-2026:30088

vendor_fix: Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://docs.re…

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Treat as emergency remediation because CISA KEV status is present.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
Kludex	starlette	< 1.0.1	Vulnerable
pip	starlette	<= 1.0.0	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

None

Confidentiality

Low

Integrity

Low

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Network

Privileges Req

None

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
6.5	CVSS 3.1	medium	3.9	2.5	GitHub (CNA), NVD, CNA, Kludex (CNA), GHSA, Red Hat (VEX)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

Unexpected State
Hide Activities
Bypass Protection Mechanism

Mitigation: Use a web server that employs a strict HTTP parsing procedure, such as Apache [REF-433].

Weakness & attack patterns

CWE-444
CWE-1289

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-33 · HTTP Request SmugglingCAPEC-105 · HTTP Request Splitting

CISA KEV details

CISA lists a CVE here once it has evidence of exploitation against real targets.

CISAThat month →

Listed

Sep 2, 2026

Federal deadline

Sep 16, 2026

in 11 days

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a date to argue against.

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

2 of the 5 sampled are weaponized

Exploit entries

Exploit-DB and CTI exploit indexes

Social mentions

Posts naming this CVE. Attention, not evidence of exploitation — it spikes on disclosure and decays whether or not anything is exploited.

35 more posts on this CVEShowing 5 of 40 · Who is discussing this CVE, and how loudlyUnlock free

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Search application, proxy, and WAF logs for requests touching /toolkit.
Prioritize edge telemetry for network-reachable starlette.
Monitor for scanner or exploit-pattern traffic after 35 public PoC repositories were reported.

web/proxy/WAF logsapplication logsnetwork IDS/IPS

Groups associated with this CVE

Groups reported in connection with this vulnerability. A reported association, not a confirmed observation of that group using it — and not scoped to any sector or campaign.

Awaken LikhoTortoiseshell

ip185.84.98.8594
AlienVault OTX Feeds · Feb 2, 2026
ip185.62.1.877
iocradar0-netizen - Public_News - Feed · Jul 11, 2026
hostnamecrazyeltonproxy.top48
AlienVault OTX Feeds · Aug 28, 2026
urlhttp://185.62.1.8/mon/mon.zip'56
Threatview.io Feeds · Aug 29, 2026

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added to CISA KEV catalog
Sep 2, 2026 · CISA
Added · CVSS 3.1 6.5 (AV:N)
Sep 2, 2026 · NVD
Added · GHSA-86qp-5c8j-p5mr published (medium)
Jun 4, 2026 · GitHub Security Advisory
Initial · CVE published
May 26, 2026 · NVD

Source activity

Readings a source repeats on a schedule, counted rather than listed.

16×SVRS was changedJun 5, 2026 – Aug 25, 2026 · SOCRadar CTI
11×TweetsJun 6, 2026 – Jul 9, 2026 · SOCRadar CTI
10×CVE modified by MITRE: CVSS metrics updated.Jun 16, 2026 – Aug 10, 2026 · SOCRadar CTI
2×Github ReposAug 3, 2026 – Aug 11, 2026 · SOCRadar CTI
1×1 time mentioned on 1 Telegram channelJun 27, 2026 · SOCRadar CTI

References

33 on the record

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

Coverage

19 stories from the feeds we poll

14 more reports on this CVEShowing 5 of 19 · Vendor research and security press coverageUnlock free

Elsewhere on this site

Kludexevery CVE for this vendor
pipevery CVE for this vendor
September 2026what else CISA listed
Unclassifiedsame class
CWE-444other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

Only the 4 indicator(s) reported for this CVE are available; no packet-level or host-forensic artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-48710 is Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks, a medium vulnerability affecting starlette from Kludex, pip. The current evidence lists it in CISA KEV, and the exploit status is: Yes: CISA KEV signal present. Public exploit evidence is: 35 public PoC repositories reported; 2 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 6.5 describes technical severity, while EPSS 2% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.