Is CVE-2026-31876 in the CISA KEV catalog?

No. CVE-2026-31876 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-31876?

CVE-2026-31876 has a CVSS v3 base score of 5.4 (MEDIUM).

What is the EPSS score for CVE-2026-31876?

CVE-2026-31876 has an EPSS score of 0.17% (7th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-31876?

Upgrade notesnook desktop to 3.3.9 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2026-31876

MEDIUM

5.4

CVSS v3

NVD

Description

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

notesnook desktopNVD

Affected:< 3.3.9Fixed in:3.3.9CVE-2026-31876derived from NVD

notesnook mobileNVD

Affected:< 3.3.15Fixed in:3.3.15CVE-2026-31876derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

0.17%probability of exploitation in 30 days

7thpercentile

Low risk: more likely to be exploited than 7% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

github.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-17.