Is CVE-2025-3523 in the CISA KEV catalog?

No. CVE-2025-3523 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-3523?

CVE-2025-3523 has a CVSS v3 base score of 6.4 (MEDIUM).

What is the EPSS score for CVE-2025-3523?

CVE-2025-3523 has an EPSS score of 0.26% (18th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-3523?

Upgrade thunderbird on debian 11 to 1:128.10.1esr-1~deb11u1 or later. Fixes are available for 9 affected products.

CVE & CISA-KEV Catalog

CVE-2025-3523

MEDIUM

6.4

CVSS v3

NVD

Description

When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only the last link is shown when hovering over any attachment. Although the correct link is used on click, the misleading hover text could trick users into downloading content from untrusted sources. This vulnerability was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.

CWE-451

How to fix

Remediation Available

thunderbirdDebian

Fixed in:1:128.10.1esr-1~deb11u1CVE-2025-3523

Fixed in:1:128.10.0esr-1~deb12u1CVE-2025-3523

Fixed in:1:128.10.0esr-1CVE-2025-3523

thunderbirdRed Hat / RHEL

Fixed in:0:128.10.0-1.el10_0RHSA-2025:7507

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_2RHSA-2025:4389

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

thunderbirdRocky

Fixed in:0:128.10.0-1.el10_0RHSA-2025:7507

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_2RHSA-2025:4389

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_2RHSA-2025:4389

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

thunderbird-debuginfoRocky

Fixed in:0:128.10.0-1.el10_0RHSA-2025:7507

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_2RHSA-2025:4389

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

thunderbird-debuginfoRed Hat / RHEL

Fixed in:0:128.10.0-1.el10_0RHSA-2025:7507

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_2RHSA-2025:4389

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

thunderbird-debugsourceRocky

Fixed in:0:128.10.0-1.el10_0RHSA-2025:7507

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_2RHSA-2025:4389

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

thunderbird-debugsourceRed Hat / RHEL

Fixed in:0:128.10.0-1.el10_0RHSA-2025:7507

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_10RHSA-2025:4649

Fixed in:0:128.9.2-1.el8_6RHSA-2025:4665

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_2RHSA-2025:4389

Fixed in:0:128.9.2-1.el8_4RHSA-2025:4654

Fixed in:0:128.9.2-1.el8_8RHSA-2025:4617

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_2RHSA-2025:4513

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_4RHSA-2025:4512

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.10.0-1.el9_6RHSA-2025:7435

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

Fixed in:0:128.9.2-1.el9_5RHSA-2025:4229

Fixed in:0:128.9.2-1.el9_0RHSA-2025:4514

thunderbirdUbuntu

Fixed in:1:128.12.0+build1-0ubuntu0.22.04.1USN-7663-1

Mozilla Thunderbird (en-US)Windows application

Affected:129.0 137.0.2Fixed in:137.0.2Mozilla

Affected:128.9.2Fixed in:128.9.2Mozilla

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 ComplexityHigh

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityHigh

AvailabilityLow

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

Exploit Intelligence

0.26%probability of exploitation in 30 days

18thpercentile

Low risk: more likely to be exploited than 18% of all known CVEs.

References

Vendor Advisory2

Other references1

bugzilla.mozilla.org

Related Vulnerabilities

Other CWE-451 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-38112	High	7.5	84%	KEV	Fix
CVE-2025-9491	High	7.8	63%	-	-
CVE-2024-43461	High	8.8	52%	KEV	Fix
CVE-2024-38197	Medium	6.5	16%	-	-
CVE-2026-21527	High	6.5	9.5%	-	Fix
CVE-2024-49040	High	7.5	7.7%	-	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 2026-04-13.