CVE-2026-75874: Sandbox escape in the Remote Settings Client component
Noroxi assessment
Priority: Plan (action score 40/100)
- 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: 0.45% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: firefox (AlmaLinux:10) 140.15.0-1.el10_2; thunderbird (AlmaLinux:10) 140.16.0-1.el10_2.alma.1; firefox (AlmaLinux:8) 140.15.0-1.el8_10.alma.1.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Add it to your regular patch cycle. Upgrade to firefox (AlmaLinux:10) 140.15.0-1.el10_2; thunderbird (AlmaLinux:10) 140.16.0-1.el10_2.alma.1; firefox (AlmaLinux:8) 140.15.0-1.el8_10.alma.1 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
Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.
- EUVD-2026-60674
- ALSA-2026:67129
- ALSA-2026:67133
- ALSA-2026:68549
- ALSA-2026:70642
- ALSA-2026:73130
- ALSA-2026:73971
- openSUSE-SU-2026:11666-1
- openSUSE-SU-2026:11678-1
- openSUSE-SU-2026:21853-1
- RHSA-2026:67129
- RHSA-2026:67133
- RHSA-2026:68549
- RHSA-2026:70642
- RHSA-2026:73130
- RHSA-2026:73971
- RHSA-2026:76740
- RHSA-2026:76741
- RHSA-2026:76742
- RHSA-2026:76745
- Published
- Aug 18, 2026
- Updated
- Sep 1, 2026
- EPSS
- 0.4% · 39th percentile
- CWE
- CWE-693
Report tools
Action score
40
Plan
Add it to your regular patch cycle.
- CVSS
- 40 / 40 · 10.0 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- 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.
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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.
We use this product, ask for helpAffected 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.
| 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 154.0.0
- mozilla thunderbirdbefore 154.0
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
- 115.40 and later · up to and including 115.*not affected · rpm
- 140.15 and later · up to and including 140.*not affected · rpm
- 153.2 and later · up to and including 153.*not affected · rpm
- 154 and laternot affected · rpm
Mozilla Thunderbird
- 140.15 and later · up to and including 140.*not affected · rpm
- 153.2 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 |
|---|---|---|---|
| AlmaLinux:10 | firefox | before 140.15.0-1.el10_2 | 140.15.0-1.el10_2 |
| AlmaLinux:10 | thunderbird | before 140.16.0-1.el10_2.alma.1 | 140.16.0-1.el10_2.alma.1 |
| AlmaLinux:8 | firefox | before 140.15.0-1.el8_10.alma.1 | 140.15.0-1.el8_10.alma.1 |
| AlmaLinux:8 | thunderbird | before 140.16.0-1.el8_10.alma.1 | 140.16.0-1.el8_10.alma.1 |
| AlmaLinux:9 | firefox | before 140.15.0-1.el9_8.alma.1 | 140.15.0-1.el9_8.alma.1 |
| AlmaLinux:9 | firefox-x11 | before 140.15.0-1.el9_8.alma.1 | 140.15.0-1.el9_8.alma.1 |
| AlmaLinux:9 | thunderbird | before 140.16.0-1.el9_8.alma.1 | 140.16.0-1.el9_8.alma.1 |
| Debian:12 | firefox-esr | before 140.15.0esr-1~deb12u1 | 140.15.0esr-1~deb12u1 |
| Debian:12 | thunderbird | before 1:140.15.0esr-1~deb12u1 | 1:140.15.0esr-1~deb12u1 |
| Debian:13 | firefox-esr | before 140.15.0esr-1~deb13u1 | 140.15.0esr-1~deb13u1 |
| Debian:13 | thunderbird | before 1:140.15.0esr-1~deb13u1 | 1:140.15.0esr-1~deb13u1 |
| Debian:14 | firefox-esr | before 140.15.0esr-1 | 140.15.0esr-1 |
| Debian:14 | thunderbird | before 1:153.2.0esr-1 | 1:153.2.0esr-1 |
| openSUSE:Leap 16.0 | MozillaFirefox | before 153.2.0-160000.1.1 | 153.2.0-160000.1.1 |
| openSUSE:Tumbleweed | firefox-esr | before 153.2.0-1.1 | 153.2.0-1.1 |
| openSUSE:Tumbleweed | MozillaThunderbird | before 140.15.0-1.1 | 140.15.0-1.1 |
| Red Hat:enterprise_linux_eus:10.0 | firefox | before 0:140.15.0-1.el10_0 | 0:140.15.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | firefox-debuginfo | before 0:140.15.0-1.el10_0 | 0:140.15.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | firefox-debugsource | before 0:140.15.0-1.el10_0 | 0:140.15.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | thunderbird | before 0:140.15.0-1.el10_0 | 0:140.15.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | thunderbird-debuginfo | before 0:140.15.0-1.el10_0 | 0:140.15.0-1.el10_0 |
| Red Hat:enterprise_linux_eus:10.0 | thunderbird-debugsource | before 0:140.15.0-1.el10_0 | 0:140.15.0-1.el10_0 |
| Red Hat:enterprise_linux:10.2 | firefox | before 0:140.15.0-1.el10_2 | 0:140.15.0-1.el10_2 |
| Red Hat:enterprise_linux:10.2 | firefox-debuginfo | before 0:140.15.0-1.el10_2 | 0:140.15.0-1.el10_2 |
+65
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
Published before and after this one in the same product
- ← EarlierCVE-2026-74984Aug 18, 2026 · Race condition in the JavaScript Engine component27Monitor
- ← EarlierCVE-2026-74986Aug 18, 2026 · Site isolation issue in the CSS Parsing and Computation component36Monitor
- Later →CVE-2026-74946Aug 18, 2026 · Information disclosure due to incorrect boundary conditions in the Graphics: CanvasWebGL component35Monitor
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:firefox | 140.15.0-1.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:firefox-x11 | 140.15.0-1.el9_8.alma.1 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:thunderbird | 140.16.0-1.el9_8.alma.1 · AlmaLinux:9 | Package registry (OSV) |
| debian:firefox-esr | 140.15.0esr-1~deb12u1 · Debian:12 | Package registry (OSV) |
| debian:thunderbird | 1:140.15.0esr-1~deb12u1 · Debian:12 | Package registry (OSV) |
| opensuse:firefox-esr | 153.2.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:MozillaFirefox | 153.2.0-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:MozillaThunderbird | 140.15.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:firefox | 0:140.15.0-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:firefox-debuginfo | 0:140.15.0-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:firefox-debugsource | 0:140.15.0-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:firefox-x11 | 0:140.15.0-1.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:thunderbird | 0:140.16.0-1.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:thunderbird-debuginfo | 0:140.16.0-1.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:thunderbird-debugsource | 0:140.16.0-1.el9_8 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| rocky linux:firefox | 0:140.15.0-1.el10_2 · Rocky Linux:10 | Package registry (OSV) |
| rocky linux:thunderbird | 0:140.16.0-1.el9_8 · Rocky Linux:9 | Package registry (OSV) |
| suse:MozillaFirefox | 153.2.0-160000.1.1 · SUSE:Linux Enterprise Server 16.0 | 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-2026-2761175 days apartSandbox escape in the Graphics: WebRender component40Plan
- CVE-2026-1637728 days apartMitigation bypass in the PDF Viewer component39Monitor
- 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.
- No user action is required.
- 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
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-693 · Protection Mechanism FailureCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
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
Show all references (7 more)Show less
- www.mozilla.org/security/advisories/mfsa2026-74/
- www.mozilla.org/security/advisories/mfsa2026-78/
- www.mozilla.org/security/advisories/mfsa2026-83/
- www.mozilla.org/security/advisories/mfsa2026-84/
- www.mozilla.org/security/advisories/mfsa2026-85/
- www.mozilla.org/security/advisories/mfsa2026-87/
- www.mozilla.org/security/advisories/mfsa2026-88/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.