CVE-2025-3909
published 2025-05-14CVE-2025-3909: 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…
PriorityP340high8.1CVSS 3.1
AVNACLPRNUIRSUCHIHAN
EPSS
0.38%
30.5th percentile
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.
Affected
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | thunderbird | < thunderbird 1:128.10.1esr-1~deb12u1 (bookworm) | thunderbird 1:128.10.1esr-1~deb12u1 (bookworm) |
| mozilla | firefox | — | — |
| mozilla | thunderbird | < 128.10.1 | 128.10.1 |
| mozilla | thunderbird | >= 0 < 1:128.10.1esr-1~deb11u1 | 1:128.10.1esr-1~deb11u1 |
| mozilla | thunderbird | >= 0 < 1:128.10.1esr-1~deb12u1 | 1:128.10.1esr-1~deb12u1 |
| mozilla | thunderbird | >= 0 < 1:128.10.1esr-1 | 1:128.10.1esr-1 |
| mozilla | thunderbird | >= 0 < 1:128.10.1esr-1 | 1:128.10.1esr-1 |
| mozilla | thunderbird | >= 129.0 < 138.0.1 | 138.0.1 |
CVSS provenance
nvdv3.18.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
osv8.1HIGH
vendor_debian8.1HIGH
vendor_redhat8.1HIGH
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GHSA
GHSA-h6cg-6m9j-xj9g: Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context
ghsa_unreviewed·2025-05-14
CVE-2025-3909 [MEDIUM] CWE-290 GHSA-h6cg-6m9j-xj9g: Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context
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 affects Thunderbird < 128.10.1 and Thunderbird < 138.0.1.
OSV
CVE-2025-3909: Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context
osv·2025-05-14·CVSS 8.1
CVE-2025-3909 [HIGH] CVE-2025-3909: Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context
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 affects Thunderbird < 128.10.1 and Thunderbird < 138.0.1.
Ubuntu
Thunderbird vulnerabilities
vendor_ubuntu·2025-07-22
CVE-2025-4083 Thunderbird vulnerabilities
Title: Thunderbird vulnerabilities
Summary: Several security issues were fixed in Thunderbird.
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context, an
attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, bypass security restrictions, cross-site
tracing, or execute arbitrary code.
Instructions: This update uses a new upstream release, which includes additional bug
fixes. After a standard system update you need to restart thunderbird to
make all the necessary changes.
Red Hat
thunderbird: JavaScript Execution via Spoofed PDF Attachment and file:/// Link
vendor_redhat·2025-05-14·CVSS 8.1
CVE-2025-3909 [HIGH] CWE-290 thunderbird: JavaScript Execution via Spoofed PDF Attachment and file:/// Link
thunderbird: JavaScript Execution via Spoofed PDF Attachment and file:/// Link
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 affects Thunderbird < 128.10.1 and Thunderbird < 138.0.1.
The Mozilla Foundation's Security Advisory describes the following issue: Thunderbird's ha
Debian
CVE-2025-3909: thunderbird - Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be ex...
vendor_debian·2025·CVSS 8.1
CVE-2025-3909 [HIGH] CVE-2025-3909: thunderbird - Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be ex...
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 affects Thunderbird < 128.10.1 and Thunderbird < 138.0.1.
Scope: local
bookworm: resolved (fixed in 1:128.10.1esr-1~deb12u1)
bullseye: resolved (fixed in 1:128.10.1esr-1~deb11u1)
forky: resolved (fixed in 1:128.10.1esr-1)
sid: re
Mozilla
Mozilla Foundation Security Advisory 2025-34: CVE-2025-3909
vendor_mozilla·CVSS 8.1
CVE-2025-3909 [HIGH] Mozilla Foundation Security Advisory 2025-34: CVE-2025-3909
Mozilla Foundation Security Advisory 2025-34
CVE: CVE-2025-3909
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 128.10.1
Mozilla
Mozilla Foundation Security Advisory 2025-35: CVE-2025-3909
vendor_mozilla·CVSS 8.1
CVE-2025-3909 [HIGH] Mozilla Foundation Security Advisory 2025-35: CVE-2025-3909
Mozilla Foundation Security Advisory 2025-35
CVE: CVE-2025-3909
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 138.0.1
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2025-05-14
Published