CVE-2026-31876 | Notesnook has Stored XSS via unsanitized Twitter/X embed URL in editor (`tweetToEmbed`)

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to 3.3.9, a Stored Cross-Site Scripting (XSS) vulnerability existed in Notesnook's editor embed component when rendering Twitter/X embed URLs. The tweetToEmbed() function in component.tsx interpolated the user-supplied URL directly into an HTML string without escaping, which was then assigned to the srcdoc attribute of an <iframe>. This vulnerability is fixed in 3.3.9.

Published: 2026-03-11 Last update: 2026-03-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-31876 is rated Low Risk (24.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-31876

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-12 — 0.03% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-31876

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.3 2.7 [email protected]

Weakness enumeration for CVE-2026-31876

Affected software / configurations for CVE-2026-31876

Vendor Product Version Raw CPE
streetwriters notesnook_desktop < 3.3.9 cpe:2.3:a:streetwriters:notesnook_desktop:*:*:*:*:*:*:*:*
streetwriters notesnook_mobile < 3.3.15 cpe:2.3:a:streetwriters:notesnook_mobile:*:*:*:*:*:android:*:*
streetwriters notesnook_mobile < 3.3.15 cpe:2.3:a:streetwriters:notesnook_mobile:*:*:*:*:*:iphone_os:*:*

References for CVE-2026-31876

cvelogic Threat Intelligence