CVE-2026-31876Public exploitNetwork attack vector

Stored XSS via unescaped Twitter embed URL

Published Mar 11, 2026 · Updated Mar 11, 2026

Stored XSS in Notesnook Web/Desktop before 3.3.9 and Android/iOS before 3.3.15 allows attackers to execute script via a crafted embed. The tweetToEmbed function interpolates the raw URL into HTML assigned to an iframe srcdoc, while its sandbox permits scripts and same-origin access. Execution requires a victim to open the note where CSP is absent or misconfigured, allowing browser-context data access and modification.

CVSS severity5.4
Medium
EPSS probability0.17%
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 Notesnook Web/Desktop before 3.3.9 and Android/iOS before 3.3.15 allows attackers to execute script via a crafted embed. The tweetToEmbed function interpolates the raw URL into HTML assigned to an iframe srcdoc, while its sandbox permits scripts and same-origin access. Execution requires a victim to open the note where CSP is absent or misconfigured, allowing browser-context data access and modification.

The record

CVE
CVE-2026-31876
Published
Mar 11, 2026
Updated
Mar 11, 2026
Vendor
Streetwriters
Product
Notesnook
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 11, 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=< 3.3.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Streetwriters · Notesnookversion=< 3.3.9

Published CVSS scores

5.4GitHub, Inc.CVSS: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 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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