VulnerabilityPublished 13 Aug 2026Updated 29 Oct 2026

CVE-2026-54282: Starlette · Unvalidated request path concatenated into authority poisons request.url.hostname

Affects mcpmSource GCVE Database

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Authoritative record:CVE-2026-54282· Low 3.7

Not known to be exploited · CVSS 3.7 Low : upgrade to 2.15.0_1 when convenient.

Data as of 30 Oct 2026, 07:00 UTC

CVSS 3.1 base score

3.7Low

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.15.0_1

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade mcpm to 2.15.0_1.

Affected software

Product	Affected	Fixed in
Homebrewmcpm`pkg:brew/mcpm`Other threats	Affected >=1.0.3 <2.15.0_1	Fixed in 2.15.0_1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Starlette to version 2.15.0_1 or later, which includes a fix that prevents the request path from crossing into the URL authority. This ensures that paths not starting with '/' are correctly handled and do not alter request.url.hostname. No other mitigation is required if the upgrade is applied.

Description

Starlette versions from 1.0.3 up to but not including 2.15.0_1 have a vulnerability where an unvalidated HTTP request path can alter the reconstructed request URL's hostname. This occurs because the path is concatenated directly after the host without ensuring it begins with a '/', allowing an attacker to craft a path that shifts the authority boundary and controls request.url.hostname. This can mislead code relying on request.url.hostname for security decisions. The issue is mitigated by upgrading to version 2.15.0_1 or later, which properly validates the path to prevent this behavior.

Impact

Applications using affected Starlette versions that rely on request.url, request.url.netloc, or request.url.hostname for security decisions may be misled by attacker-controlled hostnames. This can affect host-based authorization, redirect or callback base validation, SSRF target validation, cache keys, or audit logs. The exploitability is limited because the malformed path does not match any registered route, resulting in 404 responses and no endpoint execution. The exposure is mainly to middleware or 404/exception handlers that read request.url before routing. No known exploits are reported in the wild.

Summary

In affected Starlette versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and then re-parsing, a path not starting with '/' (e.g., '@google.com') causes the authority boundary to shift during parsing, making request.url.hostname attacker-controlled. This can mislead code that uses request.url.hostname for security-sensitive decisions such as host-based authorization or SSRF protection. The vulnerability requires an ASGI server that forwards a request-target lacking a leading '/' into scope['path']. The patched version 2.15.0_1 prevents the path from crossing into the URL authority by ensuring the path begins with '/'.

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What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 07:00 UTC

Technical details

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