CVE-2026-54249
ADVISORY - githubSummary
Summary
A client that can submit message history to a Pydantic AI UI adapter can reference arbitrary files in the application's model-provider or cloud-storage account. The server forwards the reference to the model provider, which fetches it using the server's own credentials, allowing the client to read files it should not have access to.
Details
UI adapters reconstruct file parts from client-submitted message history and forward them to the model provider. File URL parts are validated against a scheme allowlist before being forwarded, but UploadedFile references — which point to a file by provider file ID or cloud-storage URI (e.g. s3://…, gs://…) — were forwarded without validation.
Because the provider resolves an UploadedFile using the server-side identity (IAM role, service account, or provider API key) rather than the client's, a client that crafts message history containing an attacker-chosen UploadedFile can cause the server to read objects belonging to its own account or to other tenants, given a referenceable identifier.
Impact
Applications that pass untrusted client-submitted message history to an agent through a UI adapter (such as the Vercel AI adapter). Exploitation requires the attacker to reference a valid file identifier; depending on how the application names objects, such identifiers are not always unguessable.
Patches
Upgrade to 1.106.0 (1.x) or 2.0.0b6 (the 2.x beta line), which validate UploadedFile references on client-submitted messages the same way file URLs are validated.
Workarounds
If users cannot upgrade, do not pass untrusted client-submitted message history to the agent, or strip UploadedFile parts from incoming messages before running the agent.
Common Weakness Enumeration (CWE)
Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF)
GitHub
2.2
CVSS SCORE
6.8medium| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| pydantic-ai-slim | pypi | - | - | >=1.65.0,<1.106.0 | 1.106.0 |
| pydantic-ai | pypi | - | - | >=1.65.0,<1.106.0 | 1.106.0 |
| pydantic-ai | pypi | - | - | >=2.0.0b1,<2.0.0b6 | 2.0.0b6 |
| pydantic-ai-slim | pypi | - | - | >=2.0.0b1,<2.0.0b6 | 2.0.0b6 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
A successful attack depends on conditions beyond the attacker's control, requiring investing a measurable amount of effort in research, preparation, or execution against the vulnerable component before a successful attack.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any user.
An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
There is no loss of trust or accuracy within the impacted component.
There is no impact to availability within the impacted component.
NIST
2.2
CVSS SCORE
6.8mediumPypA
PYSEC-2026-3692
2.2
CVSS SCORE
6.8mediumRed Hat
2.2