CVE-2026-39418Network attack vector

SSRF via unhooked MSG_FASTOPEN sendto calls

Published Apr 14, 2026 · Updated Apr 14, 2026

SSRF in FIT2CLOUD MaxKB 2.7.1 and earlier allows remote authenticated users to reach blocked internal services through sandboxed tools. The Linux sandbox hooks connect() with LD_PRELOAD but leaves sendto() unhooked, so MSG_FASTOPEN establishes a TCP connection without banned-host validation. Tool-editing permission and execution of attacker-supplied Python are required; successful exploitation exposes services reachable from the MaxKB host.

CVSS severity5.0
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in FIT2CLOUD MaxKB 2.7.1 and earlier allows remote authenticated users to reach blocked internal services through sandboxed tools. The Linux sandbox hooks connect() with LD_PRELOAD but leaves sendto() unhooked, so MSG_FASTOPEN establishes a TCP connection without banned-host validation. Tool-editing permission and execution of attacker-supplied Python are required; successful exploitation exposes services reachable from the MaxKB host.

The record

CVE
CVE-2026-39418
Published
Apr 14, 2026
Updated
Apr 14, 2026
Vendor
KubeOperator
Product
MaxKB
Classifications
CWE-918, T1090.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

KubeOperator · MaxKBversion=< 2.8.0

Published CVSS scores

6.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L
5.0GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1090.001Internal Proxy

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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