Applications
CVE-2026-124853
Sandbox escape in Firefox/Thunderbird Graphics Text component (fixed in Firefox 160).
Major vulnerability. Critical sandbox-escape in widely used Mozilla products (Firefox/Thunderbird) enabling code execution from web/email; high CVSS and cross-industry impact warrants broad alert.
- CVSS
- 9.6Criticalscored by CISA
- Exploited in the wild
- Not knownnot in CISA KEV as of our last sync
- EPSS
- 0.41%chance of exploitation in the next 30 daystop 65% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 10 Nov 2026analysed here 12 Nov 2026
Summary
Impact
Crafted web content or email can escape the browser/mail sandbox to execute arbitrary code or access local data and secrets.
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
Products named in our analysis
- Mozilla Firefox < 160
- Firefox ESR < 115.45
- Firefox ESR < 153.7
- Mozilla Thunderbird < 160
- Thunderbird < 153.7
Fix and mitigation
Action required
Immediate action required
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Not listed as of our last sync.
- Public exploit code
- None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
- CISA SSVC
- exploitation none, automatable no, technical impact totalAssessed by CISA 10 Nov 2026 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
Timeline
- 10 Nov 2026Published
- 10 Nov 2026CISA SSVC assessment: exploitation nonesame day later
- 10 Nov 2026CVE record last updatedsame day later
- 12 Nov 2026Analysed by vulneraibility.com1 day later
Common questions
Is CVE-2026-124853 being exploited?
Not confirmed. CVE-2026-124853 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.41% probability of exploitation in the next 30 days.
How severe is CVE-2026-124853?
CVE-2026-124853 is rated Critical with a CVSS score of 9.6. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-124853?
Yes. A fix has been recorded for CVE-2026-124853. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-124853 affect?
CVE-2026-124853 affects Mozilla Firefox < 160, Firefox ESR < 115.45, Firefox ESR < 153.7, Mozilla Thunderbird < 160, and 1 further product or version. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-124853?
Update to Firefox 160/ESR 115.45 or 153.7 and Thunderbird 160/153.7 immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
6 references in the CVE record, grouped by the tags the record gives them.
Other links (6)
- bugzilla.mozilla.org /show_bug.cgi?id=2058035
- mozilla.org /security/advisories/mfsa2026-125/
- mozilla.org /security/advisories/mfsa2026-126/
- mozilla.org /security/advisories/mfsa2026-127/
- mozilla.org /security/advisories/mfsa2026-128/
- mozilla.org /security/advisories/mfsa2026-129/
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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