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CVE-2025-3909· NVD / CVE Program· CNA mozilla

JavaScript Execution via Spoofed PDF Attachment and file:/// Link

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.47% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: thunderbird (AlmaLinux:10) 128.10.1-1.el10_0.alma.1; thunderbird (AlmaLinux:8) 128.11.0-1.el8_10.alma.1; thunderbird (Debian:11) 1:128.10.1esr-1~deb11u1.

Low priority for now. Upgrade to thunderbird (AlmaLinux:10) 128.10.1-1.el10_0.alma.1; thunderbird (AlmaLinux:8) 128.11.0-1.el8_10.alma.1; thunderbird (Debian:11) 1:128.10.1esr-1~deb11u1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.

HighCVSS 8.1 · v3.1—No exploit Fix available
Published
May 14, 2025
Updated
Jun 17, 2026
EPSS
0.4% · 39th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2025-3909

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mozillathunderbird

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mozilla thunderbirdbefore 128.10.1
  • mozilla thunderbird129.0 and later · before 138.0.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mozilla). Independent of NVD's CPE analysis and usually ahead of it.

  • Mozilla Thunderbird

    • 128.10.1 and later · up to and including 128.*not affected · rpm
    • 138.0.1 and laternot affected · rpm

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10thunderbirdbefore 128.10.1-1.el10_0.alma.1128.10.1-1.el10_0.alma.1
AlmaLinux:8thunderbirdbefore 128.11.0-1.el8_10.alma.1128.11.0-1.el8_10.alma.1
Debian:11thunderbirdbefore 1:128.10.1esr-1~deb11u11:128.10.1esr-1~deb11u1
Debian:12thunderbirdbefore 1:128.10.1esr-1~deb12u11:128.10.1esr-1~deb12u1
Debian:13thunderbirdbefore 1:128.10.1esr-11:128.10.1esr-1
openSUSE:TumbleweedMozillaThunderbirdbefore 128.10.1-1.1128.10.1-1.1
Red Hat:enterprise_linux:10.0thunderbirdbefore 0:128.10.1-1.el10_00:128.10.1-1.el10_0
Red Hat:enterprise_linux:10.0thunderbird-debuginfobefore 0:128.10.1-1.el10_00:128.10.1-1.el10_0
Red Hat:enterprise_linux:10.0thunderbird-debugsourcebefore 0:128.10.1-1.el10_00:128.10.1-1.el10_0
Red Hat:enterprise_linux:8::appstreamthunderbirdbefore 0:128.11.0-1.el8_100:128.11.0-1.el8_10
Red Hat:enterprise_linux:8::appstreamthunderbird-debuginfobefore 0:128.11.0-1.el8_100:128.11.0-1.el8_10
Red Hat:enterprise_linux:8::appstreamthunderbird-debugsourcebefore 0:128.11.0-1.el8_100:128.11.0-1.el8_10
Red Hat:enterprise_linux:9::appstreamthunderbirdbefore 0:128.10.1-1.el9_60:128.10.1-1.el9_6
Red Hat:enterprise_linux:9::appstreamthunderbird-debuginfobefore 0:128.10.1-1.el9_60:128.10.1-1.el9_6
Red Hat:enterprise_linux:9::appstreamthunderbird-debugsourcebefore 0:128.10.1-1.el9_60:128.10.1-1.el9_6
Red Hat:rhel_aus:8.2::appstreamthunderbirdbefore 0:128.10.1-1.el8_20:128.10.1-1.el8_2
Red Hat:rhel_aus:8.2::appstreamthunderbird-debuginfobefore 0:128.10.1-1.el8_20:128.10.1-1.el8_2
Red Hat:rhel_aus:8.2::appstreamthunderbird-debugsourcebefore 0:128.10.1-1.el8_20:128.10.1-1.el8_2
Red Hat:rhel_aus:8.4::appstreamthunderbirdbefore 0:128.10.1-1.el8_40:128.10.1-1.el8_4
Red Hat:rhel_aus:8.4::appstreamthunderbird-debuginfobefore 0:128.10.1-1.el8_40:128.10.1-1.el8_4
Red Hat:rhel_aus:8.4::appstreamthunderbird-debugsourcebefore 0:128.10.1-1.el8_40:128.10.1-1.el8_4
Red Hat:rhel_aus:8.6::appstreamthunderbirdbefore 0:128.10.1-1.el8_60:128.10.1-1.el8_6
Red Hat:rhel_aus:8.6::appstreamthunderbird-debuginfobefore 0:128.10.1-1.el8_60:128.10.1-1.el8_6
Red Hat:rhel_aus:8.6::appstreamthunderbird-debugsourcebefore 0:128.10.1-1.el8_60:128.10.1-1.el8_6

+17

Same product

mozilla: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-11705A flaw in Thunderbird's implementation of iCal causes a stack buffer overflow in icalrecur_add_bydayrules when processing certain email mess
    42Plan
  • CVE-2019-11704A flaw in Thunderbird's implementation of iCal causes a heap buffer overflow in icalmemory_strdup_and_dequote when processing certain email
    42Plan
  • CVE-2019-11703A flaw in Thunderbird's implementation of iCal causes a heap buffer overflow in parser_get_next_char when processing certain email messages,
    42Plan

Published before and after this one in the same product

  • ← EarlierCVE-2025-3523Apr 15, 2025 · User Interface (UI) Misrepresentation of attachment URL
    25Monitor
  • ← EarlierCVE-2025-3875May 14, 2025 · Sender Spoofing via Malformed From Header in Thunderbird
    30Monitor
  • Later →CVE-2025-3932May 14, 2025 · Tracking Links in Attachments Bypassed Remote Content Blocking
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:thunderbird128.10.1-1.el10_0.alma.1 · AlmaLinux:10Package registry (OSV)
debian:thunderbird1:128.10.1esr-1~deb12u1 · Debian:12Package registry (OSV)
opensuse:MozillaThunderbird128.10.1-150200.8.215.1 · openSUSE:Leap 15.6Package registry (OSV)
red hat:thunderbird0:128.10.1-1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:thunderbird-debuginfo0:128.10.1-1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:thunderbird-debugsource0:128.10.1-1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
rocky linux:thunderbird0:128.10.1-1.el10_0 · Rocky Linux:10Package registry (OSV)
suse:MozillaThunderbird128.10.1-150200.8.215.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP6Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-356 · Product UI does not Warn User of Unsafe Actions

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records