CVE-2022-4866Public exploitNetwork attack vector

Stored script execution via unescaped Markdown formatting

Published Dec 31, 2022 · Updated Apr 9, 2025

Stored cross-site scripting in Memos before 0.9.1 allows remote authenticated users to execute script in another user's browser. The Markdown renderer parsed bold, emphasis, and link-label content without invoking PlainText escaping, so stored markup reached generated HTML. An attacker must store a crafted memo and a victim must view the rendered content; script then runs with the victim's Memos origin privileges.

CVSS severity9.8
Critical
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Memos before 0.9.1 allows remote authenticated users to execute script in another user's browser. The Markdown renderer parsed bold, emphasis, and link-label content without invoking PlainText escaping, so stored markup reached generated HTML. An attacker must store a crafted memo and a victim must view the rendered content; script then runs with the victim's Memos origin privileges.

The record

CVE
CVE-2022-4866
Published
Dec 31, 2022
Updated
Apr 9, 2025
Vendor
Memos
Product
Memos
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 31, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2025Record 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=unspecified <0.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Memos · Memosversion=unspecified <0.9.1

Published CVSS scores

9.8huntr.devCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.0NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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