Mitigation bypass in the Data Loss Prevention component
Mitigation bypass in the Data Loss Prevention component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
- Published
- Aug 18, 2026
- Updated
- Sep 17, 2026
- EPSS
- 0.4% · 35th percentile
- CWE
- CWE-693
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Report tools
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.
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 helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| mozilla | firefox | cpe:2.3:a:mozilla:firefox |
| 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 firefoxbefore 140.14.0
- mozilla firefox141.0 and later · before 153.1.0
- mozilla thunderbirdbefore 140.14.0
- mozilla thunderbird141.0 and later · before 153.1.0
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 Firefox
- 140.14 and later · up to and including 140.*not affected · rpm
- 153.1 and later · up to and including 153.*not affected · rpm
- 154 and laternot affected · rpm
Mozilla Thunderbird
- 140.14 and later · up to and including 140.*not affected · rpm
- 153.1 and later · up to and including 153.*not affected · rpm
- 154 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 |
|---|---|---|---|
| Debian:12 | firefox-esr | before 140.14.0esr-1~deb12u1 | 140.14.0esr-1~deb12u1 |
| Debian:12 | thunderbird | before 1:140.14.0esr-1~deb12u1 | 1:140.14.0esr-1~deb12u1 |
| Debian:13 | firefox-esr | before 140.14.0esr-1~deb13u1 | 140.14.0esr-1~deb13u1 |
| Debian:13 | thunderbird | before 1:140.14.0esr-1~deb13u1 | 1:140.14.0esr-1~deb13u1 |
| Debian:14 | firefox-esr | before 140.14.0esr-2 | 140.14.0esr-2 |
| Debian:14 | thunderbird | before 1:140.14.0esr-1 | 1:140.14.0esr-1 |
Same product
mozilla: all recordsOther highest-scoring records for the same primary product.
- CVE-2010-3765Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x befKEV94Now
- CVE-2019-11708Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxeKEV87Now
- CVE-2015-4495The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote attackers to bypassKEV86Now
- CVE-2013-1690Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before 17.0.7 do not properKEV86Now
- CVE-2019-17026Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion.KEV79This week
- CVE-2024-9680An attacker was able to achieve code execution in the content process by exploiting a use-after-free in Animation timelines.KEV76This week
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 |
|---|---|---|
| debian:firefox-esr | 140.14.0esr-1~deb12u1 · Debian:12 | Package registry (OSV) |
| debian:thunderbird | 1:140.14.0esr-1~deb12u1 · Debian:12 | 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.
- CVE-2026-758740 days apartSandbox escape in the Remote Settings Client component40Plan
- CVE-2026-2761175 days apartSandbox escape in the Graphics: WebRender component40Plan
- CVE-2026-1638228 days apartMitigation bypass in the DOM: Service Workers component39Monitor
- CVE-2026-1638328 days apartMitigation bypass in the DOM: Networking component39Monitor
- CVE-2026-1638828 days apartSandbox escape in the DOM: Networking component39Monitor
- CVE-2026-9206628 days apartSandbox escape in the Profile Backup component39Monitor
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).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-0864 · Aug 19, 2026(Mozilla Firefox Güvenlik Bildirimi)
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-693 · Protection Mechanism FailureCVSS 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.
Attack patterns (CAPEC)
- Accessing Functionality Not Properly Constrained by ACLsCAPEC-1likelihood: High · High
- Cross Site TracingCAPEC-107likelihood: Medium · Very High
- Directory IndexingCAPEC-127likelihood: High · Medium
- Using Malicious FilesCAPEC-17likelihood: High · Very High
- Encryption Brute ForcingCAPEC-20likelihood: Low · Low
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- Escaping a Sandbox by Calling Code in Another LanguageCAPEC-237likelihood: Low · Very High
- Using Unpublished Interfaces or FunctionalityCAPEC-36likelihood: Medium · High
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- bugzilla.mozilla.org/show_bug.cgi?id=2051897
- www.mozilla.org/security/advisories/mfsa2026-74/
- www.mozilla.org/security/advisories/mfsa2026-76/
- www.mozilla.org/security/advisories/mfsa2026-77/
- www.mozilla.org/security/advisories/mfsa2026-78/
- www.mozilla.org/security/advisories/mfsa2026-79/
- www.mozilla.org/security/advisories/mfsa2026-80/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.