CVE-2025-47277
Description
A flaw was found in vLLM. This vulnerability allows unauthorized access to key-value caches via network exposure of the TCPStore interface when using the PyNcclPipe KV cache transfer integration with the V0 engine.
Security Bulletin
Statement
By default, Red Hat products are configured to restrict vLLM nodes to an isolated network. However, this vulnerability could become relevant if customers change the specific configurations, and therefore, Red Hat products are affected.
This vulnerability is classified as Moderate rather than Critical because its exploitability and impact are constrained by specific deployment contexts and assumptions about network trust boundaries. While the use of pickle.loads on untrusted input typically leads to remote code execution (RCE), the vulnerable PyNcclPipe interface is not intended to be exposed to the internet or untrusted networks, it is designed for use within a secured, internal cluster environment as explicitly documented by vLLM. Successful exploitation requires an attacker to have direct network access to a misconfigured or poorly segmented system where the KV cache transfer service is bound to a public interface. Additionally, the vulnerable code path exists only in a niche configuration (V0 engine with PyNcclPipe), further reducing its exposure. Therefore, while the flaw does introduce RCE risk in misconfigured setups, the combination of non-default exposure, clear documentation, and limited applicability justifies a reduced impact.
Mitigation
No mitigation is currently available that meets Red Hat Product Security’s standards for usability, deployment, applicability, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 9.8 |
| Attack Vector | Adjacent Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data; Unexpected State
Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
Availability
Technical Impact: DoS: Resource Consumption (CPU)
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
Other
Technical Impact: Varies by Context
The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.
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