CVE-2026-58593Public exploitNetwork attack vector

Unauthenticated content forgery via unbound ActivityPub author

Published Jul 1, 2026 · Updated Jul 1, 2026

Authentication bypass in NodeBB 4.13.2 allows remote attackers to forge posts and private messages as arbitrary local users via ActivityPub. The inbound object mock copies a numeric attributedTo value directly into the local uid field while actor validation discards numeric identifiers instead of binding them to the signed remote actor. Exploitation requires federation to be enabled and permits stored content to appear under any selected local account, including an administrator account.

CVSS severity8.7
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in NodeBB 4.13.2 allows remote attackers to forge posts and private messages as arbitrary local users via ActivityPub. The inbound object mock copies a numeric attributedTo value directly into the local uid field while actor validation discards numeric identifiers instead of binding them to the signed remote actor. Exploitation requires federation to be enabled and permits stored content to appear under any selected local account, including an administrator account.

The record

CVE
CVE-2026-58593
Published
Jul 1, 2026
Updated
Jul 1, 2026
Vendor
NodeBB
Product
NodeBB
Classifications
CWE-345, CWE-290, T1659
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 1, 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=4.13.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NodeBB · NodeBBversion=4.13.2

Published CVSS scores

7.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
CWE-290Authentication Bypass by Spoofing
T1659Content Injection

Public exploit references

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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