Privilege escalation in the Netmonitor component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
CVE-2026-4717
“—” beside the score: it is equal to NVD's CVSS score.
Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-03-24. NVD baseline CVSS 9.8; sources differ by 0.0.
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALmedium confidence
- EG Risk
- 59EG Risk 59/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity98% × 45%Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.4% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.4%
- EPSS %ILE
- 34th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-18). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
March 24, 2026
Last Modified
June 17, 2026
Advisory Details (5)
Auto-updated Oct 13, 2026Security Vulnerabilities fixed in Thunderbird 140.9 — Mozilla
https://www.mozilla.org/security/advisories/mfsa2026-24/Security Vulnerabilities fixed in Thunderbird 149 — Mozilla
https://www.mozilla.org/security/advisories/mfsa2026-23/Security Vulnerabilities fixed in Firefox ESR 140.9 — Mozilla
https://www.mozilla.org/security/advisories/mfsa2026-22/Security Vulnerabilities fixed in Firefox 149 — Mozilla
https://www.mozilla.org/security/advisories/mfsa2026-20/2021695 - (CVE-2026-4717) JavaScript injection via DevTools "Copy as Fetch" / "Use as Fetch in Console" with data: URIs
https://bugzilla.mozilla.org/show_bug.cgi?id=2021695Vendor Advisories for CVE-2026-4717(20)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:8850Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- RHSA-2026:8427Red Hat Product SecurityHigh
Red Hat Security Advisory: firefox security update
- RHSA-2026:8315Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- RHSA-2026:8290Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- RHSA-2026:8284Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- RHSA-2026:8289Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- RHSA-2026:8286Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- RHSA-2026:8287Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- +12 more
Patch Availability(25)
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(8 across 4 ecosystems)
Debian:11(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| firefox-esr | 102.1.0esr-1 ... 91.9.1esr-1~deb9u1 (255 versions) |
| — |
| thunderbird | 1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (306 versions) |
| — |
Debian:12(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| firefox-esr | 102.11.0esr-1 ... 140.8.0esr-1~deb13u1 (161 versions) |
| — |
| thunderbird | 1:102.11.0-1 ... 1:140.9.0esr-1~deb11u1 (191 versions) |
| — |
Debian:13(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| firefox-esr | 128.13.0esr-1 ... 140.8.0esr-1~deb13u1 (36 versions) |
| — |
| thunderbird | 1:128.13.0esr-1 ... 1:140.9.0esr-1~deb11u1 (46 versions) |
| — |
Debian:14(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| firefox-esr | 128.13.0esr-1 ... 140.9.0esr-1~deb13u1 (39 versions) |
| — |
| thunderbird | 1:128.13.0esr-1 ... 1:140.9.0esr-1~deb13u1 (48 versions) |
| — |
Additional Vendor Advisories
(5)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
- Red HatRHSA-2026:5930MODERATE2026-03-24
RHSA-2026:5930 — Moderate
- Red HatRHSA-2026:5931MODERATE2026-03-24
RHSA-2026:5931 — Moderate
- Red HatRHSA-2026:5932MODERATE2026-03-24
RHSA-2026:5932 — Moderate
- Red HatRHSA-2026:6188MODERATE2026-03-24
RHSA-2026:6188 — Moderate
- Red HatRHSA-2026:6342MODERATE2026-03-24
RHSA-2026:6342 — Moderate
Data Freshness Timeline
(refreshed 25× in last 7d / 52× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 100 of 300 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 200 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-19 13:25 UTCEG score recompute
- 2026-10-19 13:25 UTCVendor advisory
- 2026-10-19 13:25 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-18 13:18 UTCVendor advisory
- 2026-10-18 13:18 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 03:36 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-17 13:55 UTCEG score recompute
- 2026-10-17 13:55 UTCVendor advisory
- 2026-10-17 13:55 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-16 14:31 UTCEG score recompute
- 2026-10-16 14:31 UTCVendor advisory
- 2026-10-16 14:30 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-15 14:59 UTCEG score recompute
- 2026-10-15 14:59 UTCVendor advisory
- 2026-10-15 14:59 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-14 09:27 UTCEG score recompute
- 2026-10-14 09:27 UTCVendor advisory
- 2026-10-14 09:26 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
Show 75 moreShow fewer
- 2026-10-13 06:57 UTCEG score recompute
- 2026-10-13 06:57 UTCVendor advisory
- 2026-10-13 06:57 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-12 16:02 UTCEG score recompute
- 2026-10-12 07:34 UTCVendor advisory
- 2026-10-12 07:33 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-11 19:45 UTCEG score recompute
- 2026-10-11 16:59 UTCEG score recompute
- 2026-10-11 14:24 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-16 10:39 UTCEG score recompute
- 2026-08-16 10:39 UTCVendor advisory
- 2026-08-16 10:39 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-14 23:45 UTCVendor advisory
- 2026-08-14 23:45 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-08-14 19:41 UTCVendor advisory
- 2026-08-14 19:41 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-08-14 15:02 UTCVendor advisory
- 2026-08-14 15:02 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-08-14 10:55 UTCVendor advisory
- 2026-08-14 10:55 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-08-14 06:52 UTCEG score recompute
- 2026-08-14 06:52 UTCVendor advisory
- 2026-08-14 06:52 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-13 01:34 UTCVendor advisory
- 2026-08-13 01:34 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-08-12 21:31 UTCEG score recompute
- 2026-08-12 21:31 UTCVendor advisory
- 2026-08-12 21:31 UTCGHSA enrichmentGHSA-pqfx-cwf8-965q · GitHub severity CRITICAL · GitHub CVSS 9.8
Related CVEs(same vendor)
Same vendor
10 shownredhat:RHSA-2026:5930
Frequently asked(5)
What is CVE-2026-4717?
When was the CVE record for CVE-2026-4717 published?
Is CVE-2026-4717 actively exploited?
What is the CVSS score of CVE-2026-4717?
How do I remediate CVE-2026-4717?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-4717
Is Your Infrastructure Affected by CVE-2026-4717?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.