CVE-2023-5057Network attack vector

Stored XSS via unescaped mention metadata

Published Oct 16, 2023 · Updated Aug 2, 2024

Stored XSS in Automattic ActivityPub before 1.0.0 allows remote authenticated users to execute scripts through crafted user metadata. Mention generation outputs unescaped WordPress user metadata into rendered pages instead of HTML-escaping it. Contributor-level access is required, and the injected script runs when another user views an affected mention.

CVSS severity5.4
Medium
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Automattic ActivityPub before 1.0.0 allows remote authenticated users to execute scripts through crafted user metadata. Mention generation outputs unescaped WordPress user metadata into rendered pages instead of HTML-escaping it. Contributor-level access is required, and the injected script runs when another user views an affected mention.

The record

CVE
CVE-2023-5057
Published
Oct 16, 2023
Updated
Aug 2, 2024
Vendor
Automattic
Product
ActivityPub
Classifications
T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 16, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record 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=0 <1.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Automattic · ActivityPubversion=0 <1.0.0

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A: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.

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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

T1059.007Command and Scripting Interpreter: JavaScript/JScript

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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