VulnerabilityPublished 13 Aug 2026Updated 29 Oct 2026

CVE-2026-48817: Starlette · Arbitrary HTTP method dispatched to `HTTPEndpoint` attributes via `getattr`

Affects mcp-atlassianSource GCVE Database

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Authoritative record:CVE-2026-48817· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium : upgrade to 0.21.1_8 when convenient.

Data as of 30 Oct 2026, 08:16 UTC

CVSS 3.1 base score

5.3Medium

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

Patch: Available – fixed in 0.21.1_8

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

Attack Vector: Network
Attack Complexity: Low
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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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 17 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 mcp-atlassian to 0.21.1_8.

Affected software

Product	Affected	Fixed in
Homebrewmcp-atlassian`pkg:brew/mcp-atlassian`Other threats	Affected >=0.11.9 <0.21.1_8	Fixed in 0.21.1_8

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

AI-suggested

To mitigate this vulnerability, always register HTTPEndpoint subclasses with an explicit methods= argument listing only the supported HTTP verbs. This ensures that unsupported methods are rejected with a 405 Method Not Allowed response before reaching the endpoint, preventing invocation of internal attributes via non-standard HTTP methods. A patch is available in Starlette version 0.21.1_8, which should be applied to affected deployments.

Description

Starlette's HTTPEndpoint dispatches HTTP methods by lowercasing the method name and using getattr without restricting to known HTTP verbs. If an HTTPEndpoint subclass is registered without specifying allowed methods, non-standard HTTP methods can invoke internal attributes as handlers, potentially bypassing authorization. This affects Starlette versions >=0.11.9 and <0.21.1_8 and frameworks built on it like FastAPI. The vulnerability is medium severity with a CVSS score of 5.3.

Impact

An attacker can send a non-standard HTTP method that matches an internal method name on an HTTPEndpoint subclass registered without method restrictions. This causes the internal method to be invoked as a request handler, potentially bypassing authorization checks and exposing internal functionality not intended for HTTP access. This impacts applications using affected Starlette versions and frameworks built on it, such as FastAPI, if they do not explicitly restrict HTTP methods on routes.

Summary

The vulnerability arises because HTTPEndpoint resolves the handler method by lowercasing the client-supplied HTTP method and using getattr on the endpoint instance without validating the method against a known set of HTTP verbs. When a route is registered without an explicit methods= argument, all HTTP methods are accepted, allowing non-standard methods whose lowercase names match internal attributes to be invoked as request handlers. This can lead to unauthorized access to internal methods that were not intended as HTTP handlers. The issue affects Starlette versions from 0.11.9 up to but not including 0.21.1_8. The vulnerability is mitigated by explicitly specifying allowed HTTP methods in the Route registration, causing unsupported methods to be rejected with a 405 status before reaching the endpoint.

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What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 08:16 UTC

Technical details

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