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BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization

Not in CISA KEVMetasploit moduleCVE-2025-27520CWE-502

Not confirmed exploited. 1 of 8 rule sources name it.

Edge rules
1/8
Our test
No exploit yet
CVSS
9.8
EPSS
40.6% Top 1%
Posts, 14d
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Published
2025-04-04
BentoML is a Python library for building online serving systems optimized for AI apps and model inference. A Remote Code Execution (RCE) vulnerability caused by insecure deserialization has been identified in the latest version (v1.4.2) of… More

BentoML is a Python library for building online serving systems optimized for AI apps and model inference. 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. It exists an unsafe code segment in serde.py. This vulnerability is fixed in 1.4.3.

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Ask about CVE-2025-27520: who's covered, what to patch first, how vendors compare. I cite sources and won't help with attacks.

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Severity, decoded

CVSS 3.1
Critical · 9.8 / 10

Exploitable over the network, with no privileges and no user interaction, leading to full loss of confidentiality, integrity and availability.

Over the internetNo login neededNo user actionWorks reliablyFull compromise
How the score is built8 metrics
  • Attack vectorAn attacker can reach it over the internet; no access to your network needed.
    Network
  • Attack complexityNo special conditions are needed; the attack works reliably.
    Low
  • Privileges requiredNo account or login is needed.
    None
  • User interactionNo one has to click or open anything; the attack works on its own.
    None
  • ScopeThe damage stays within the vulnerable component.
    Unchanged
  • Confidentiality impactAn attacker can read all data the affected component holds, or the most sensitive parts of it.
    High
  • Integrity impactAn attacker can change any data or files the affected component protects.
    High
  • Availability impactAn attacker can take the component down completely or keep it from serving anyone.
    High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA's assessmentSSVC, from the CVE record
ExploitationProof of concept

Public exploit code or a detailed write-up exists, but CISA has not seen attacks.

AutomatableYes

Attackers can script the attack end to end and hit many targets at once.

Technical impactTotal

A successful attack gives full control over the affected software or all of its data.

Public exploits

1 found
1 Metasploit0 Exploit-DB0 Scanner template0 GitHub PoCs
  • MetasploitBentoML RCE2025-04-04 · exploit · rank Excellent · has check

Links are to third-party code: never run it outside an isolated lab.

Timeline

  1. 2025-04-04
    CVE published
    CVE List
  2. 2025-04-04
    Metasploit module published
    BentoML RCE
  3. 2025-05-19
    Cloudflare ships a rule
    BentoML - Remote Code Execution - CVE:CVE-2025-27520

Social

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No posts seen yet on X, Bluesky, Mastodon, Hacker News or GitHub.

Vendor statements

Quoted
CloudflareWAF Managed Rules1 quoteRule off by default

First rule 2025-05-19, 45 days after the CVE was published.

2025-05-19New rule…d7619ccbDefault: DisabledSource
BentoML - Remote Code Execution - CVE:CVE-2025-27520. Previous action: Log. New action: Disabled. This is a New Detection
AWSAWS WAF Managed RulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. AWS often describes a vulnerability without naming its CVE (for example "Log4j"). We count only entries that name the CVE, so AWS coverage is understated.

Microsoft AzureFront Door and Application Gateway WAF (DRS)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. The rule tables name CVEs but carry no dates, so Azure is left out of every time-to-rule figure.

Google CloudCloud Armor preconfigured WAF rulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Google names few CVEs: the release notes start in May 2024 and the rules reference lists CVEs without dates. Its cve-canary rules are opt-in.

FastlyNext-Gen WAF virtual patchesBefore feed history

The CVE predates the oldest entry in this vendor's public feed, so a rule may exist that we cannot see.

F5Attack signatures (Distributed Cloud WAF)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Each signature lists the CVEs it references, with its id and date. F5 does not state a default action; signatures enforce once staging ends in your policy.

AkamaiApp & API Protector (Adaptive Security Engine)No public source

This vendor publishes no machine-readable rule changelog we can check.

OWASP CRSCore Rule Set (open source, used inside many WAFs)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. CRS rarely names CVEs: it relies on generic detections. Our own lab measures what it actually blocks.