Tracking Links in Attachments Bypassed Remote Content Blocking
It was possible to craft an email that showed a tracking link as an attachment. If the user attempted to open the attachment, Thunderbird automatically accessed the link. The configuration to block remote content did not prevent that. Thunderbird has been fixed to no longer allow access to web pages listed in the X-Mozilla-External-Attachment-URL header of an email. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.
- BDU:2025-08557
- ALSA-2025:8196
- ALSA-2025:8756
- DLA-4167-1
- DSA-5921-1
- openSUSE-SU-2025:15131-1
- RHSA-2025:8196
- RHSA-2025:8203
- RHSA-2025:8324
- RHSA-2025:8325
- RHSA-2025:8326
- RHSA-2025:8391
- RHSA-2025:8507
- RHSA-2025:8594
- RHSA-2025:8756
- RHSA-2025:8784
- RLSA-2025:8196
- RLSA-2025:8203
- RLSA-2025:8756
- SUSE-SU-2025:01660-1
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for help- Published
- May 14, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.4% · 29th percentile
- CWE
- CWE-288
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Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| mozilla | thunderbird | cpe:2.3:a:mozilla:thunderbird |
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.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | thunderbird | before 128.10.1-1.el10_0.alma.1 | 128.10.1-1.el10_0.alma.1 |
| AlmaLinux:8 | thunderbird | before 128.11.0-1.el8_10.alma.1 | 128.11.0-1.el8_10.alma.1 |
| Debian:11 | thunderbird | before 1:128.10.1esr-1~deb11u1 | 1:128.10.1esr-1~deb11u1 |
| Debian:12 | thunderbird | before 1:128.10.1esr-1~deb12u1 | 1:128.10.1esr-1~deb12u1 |
| Debian:13 | thunderbird | before 1:128.10.1esr-1 | 1:128.10.1esr-1 |
| openSUSE:Tumbleweed | MozillaThunderbird | before 128.10.1-1.1 | 128.10.1-1.1 |
| Red Hat:enterprise_linux:10.0 | thunderbird | before 0:128.10.1-1.el10_0 | 0:128.10.1-1.el10_0 |
| Red Hat:enterprise_linux:10.0 | thunderbird-debuginfo | before 0:128.10.1-1.el10_0 | 0:128.10.1-1.el10_0 |
| Red Hat:enterprise_linux:10.0 | thunderbird-debugsource | before 0:128.10.1-1.el10_0 | 0:128.10.1-1.el10_0 |
| Red Hat:enterprise_linux:8::appstream | thunderbird | before 0:128.11.0-1.el8_10 | 0:128.11.0-1.el8_10 |
| Red Hat:enterprise_linux:8::appstream | thunderbird-debuginfo | before 0:128.11.0-1.el8_10 | 0:128.11.0-1.el8_10 |
| Red Hat:enterprise_linux:8::appstream | thunderbird-debugsource | before 0:128.11.0-1.el8_10 | 0:128.11.0-1.el8_10 |
| Red Hat:enterprise_linux:9::appstream | thunderbird | before 0:128.10.1-1.el9_6 | 0:128.10.1-1.el9_6 |
| Red Hat:enterprise_linux:9::appstream | thunderbird-debuginfo | before 0:128.10.1-1.el9_6 | 0:128.10.1-1.el9_6 |
| Red Hat:enterprise_linux:9::appstream | thunderbird-debugsource | before 0:128.10.1-1.el9_6 | 0:128.10.1-1.el9_6 |
| Red Hat:rhel_aus:8.2::appstream | thunderbird | before 0:128.10.1-1.el8_2 | 0:128.10.1-1.el8_2 |
| Red Hat:rhel_aus:8.2::appstream | thunderbird-debuginfo | before 0:128.10.1-1.el8_2 | 0:128.10.1-1.el8_2 |
| Red Hat:rhel_aus:8.2::appstream | thunderbird-debugsource | before 0:128.10.1-1.el8_2 | 0:128.10.1-1.el8_2 |
| Red Hat:rhel_aus:8.4::appstream | thunderbird | before 0:128.10.1-1.el8_4 | 0:128.10.1-1.el8_4 |
| Red Hat:rhel_aus:8.4::appstream | thunderbird-debuginfo | before 0:128.10.1-1.el8_4 | 0:128.10.1-1.el8_4 |
| Red Hat:rhel_aus:8.4::appstream | thunderbird-debugsource | before 0:128.10.1-1.el8_4 | 0:128.10.1-1.el8_4 |
| Red Hat:rhel_aus:8.6::appstream | thunderbird | before 0:128.10.1-1.el8_6 | 0:128.10.1-1.el8_6 |
| Red Hat:rhel_aus:8.6::appstream | thunderbird-debuginfo | before 0:128.10.1-1.el8_6 | 0:128.10.1-1.el8_6 |
| Red Hat:rhel_aus:8.6::appstream | thunderbird-debugsource | before 0:128.10.1-1.el8_6 | 0:128.10.1-1.el8_6 |
+17
Same product
mozilla: all recordsOther 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 mess42Plan
- 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
- CVE-2015-2740Buffer overflow in the nsXMLHttpRequest::AppendToResponseText function in Mozilla Firefox before 39.0, Firefox ESR 31.x before 31.8 and 38.x42Plan
- CVE-2013-5603Use-after-free vulnerability in the nsContentUtils::ContentIsHostIncludingDescendantOf function in Mozilla Firefox before 25.0, Firefox ESR 42Plan
- CVE-2013-1719Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 24.0, Thunderbird before 24.0, and SeaMonkey before 2.242Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| almalinux:thunderbird | 128.10.1-1.el10_0.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| debian:thunderbird | 1:128.10.1esr-1~deb12u1 · Debian:12 | Package registry (OSV) |
| opensuse:MozillaThunderbird | 128.10.1-150200.8.215.1 · openSUSE:Leap 15.6 | Package registry (OSV) |
| red hat:thunderbird | 0:128.10.1-1.el10_0 · Red Hat:enterprise_linux:10.0 | Package registry (OSV) |
| red hat:thunderbird-debuginfo | 0:128.10.1-1.el10_0 · Red Hat:enterprise_linux:10.0 | Package registry (OSV) |
| red hat:thunderbird-debugsource | 0:128.10.1-1.el10_0 · Red Hat:enterprise_linux:10.0 | Package registry (OSV) |
| rocky linux:thunderbird | 0:128.10.1-1.el10_0 · Rocky Linux:10 | Package registry (OSV) |
| suse:MozillaThunderbird | 128.10.1-150200.8.215.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP6 | Package 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.
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 researchersFinders, 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
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-288 · Authentication Bypass Using an Alternate Path or ChannelCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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.
Attack patterns (CAPEC)
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- bugzilla.mozilla.org/show_bug.cgi?id=1960412
- www.mozilla.org/security/advisories/mfsa2025-34/
- www.mozilla.org/security/advisories/mfsa2025-35/
- lists.debian.org/debian-lts-announce/2025/05/msg00022.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.