Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
CVE-2026-3889
“—” beside the score: it is equal to NVD's CVSS score.
Score 6.5 from GitHub Security Advisory published 2026-03-24. NVD baseline CVSS 6.5; sources differ by 0.0.
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.5
- EG Score
- 6.5MEDIUMmedium confidence
- EG Risk
- 29EG Risk 29/100
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)Severity65% × 45%Impact severity (EG Severity): CVSS 6.5 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.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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. - EPSS PROB
- 0.4%
- EPSS %ILE
- 27th
- 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 (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.5 MEDIUMCVSS-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 2026-10-17). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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 every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (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 (3)
Auto-updated Aug 4, 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/Vendor Advisories for CVE-2026-3889(12)
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-2026:8315Red 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
- RHSA-2026:8288Red Hat Product SecurityHigh
Red Hat Security Advisory: thunderbird security update
- +4 more
Patch Availability(12)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| redhat | thunderbird-0:140.9.0-1.el8_4 | 2026-04-20 | redhat |
| redhat | thunderbird-0:140.9.0-1.el9_0 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el8_6 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el8_8 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el9_4 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el9_6 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el8_2 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el10_0 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el9_2 | 2026-04-15 | redhat |
| redhat | thunderbird-0:140.9.0-1.el8_10 | 2026-04-07 | redhat |
| redhat | thunderbird-0:140.9.0-1.el10_1 | 2026-04-01 | redhat |
| redhat | thunderbird-0:140.9.0-1.el9_7 | 2026-03-30 | redhat |
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
(4 across 4 ecosystems)
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| thunderbird | 1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (306 versions) |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| thunderbird | 1:102.11.0-1 ... 1:140.9.0esr-1~deb11u1 (191 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| thunderbird | 1:128.13.0esr-1 ... 1:140.9.0esr-1~deb11u1 (46 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| thunderbird | 1:128.13.0esr-1 ... 1:140.9.0esr-1~deb13u1 (48 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 28× 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 99 of 211 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. 1 repeat row among the latest 100 is merged into the row it repeats. The 112 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% · 27th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-18 03:44 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-12 16:10 UTCEG score recompute
- 2026-10-11 19:52 UTCEG score recompute
- 2026-10-11 17:06 UTCEG score recompute
- 2026-10-11 14:32 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.4% · 27th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 26th percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 26th percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.4% · 26th percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 26th percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 26th percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 26th percentile
Show 74 moreShow fewer
- 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.4% · 26th percentile
- 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.4% · 26th percentile
- 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-16 10:30 UTCEG score recompute
- 2026-08-16 10:30 UTCVendor advisory
- 2026-08-16 10:30 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-14 06:48 UTCEG score recompute
- 2026-08-14 06:48 UTCVendor advisory
- 2026-08-14 06:48 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-12 22:42 UTCEG score recompute
- 2026-08-12 22:42 UTCVendor advisory
- 2026-08-12 22:42 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-11 21:03 UTCEG score recompute
- 2026-08-11 21:03 UTCVendor advisory
- 2026-08-11 21:03 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-11 13:43 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-10 08:03 UTCEG score recompute
- 2026-08-10 08:03 UTCVendor advisory
- 2026-08-10 08:03 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-09 06:24 UTCVendor advisory
- 2026-08-09 06:24 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-07 16:43 UTCEG score recompute
- 2026-08-07 16:43 UTCVendor advisory
- 2026-08-07 16:43 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-06 01:09 UTCEG score recompute
- 2026-08-06 01:09 UTCVendor advisory
- 2026-08-06 01:09 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-04 10:38 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-03 23:54 UTCEG score recompute
- 2026-08-03 23:54 UTCVendor advisory
- 2026-08-03 23:54 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-08-02 15:43 UTCEG score recompute
- 2026-08-02 15:43 UTCVendor advisory
- 2026-08-02 15:43 UTCGHSA enrichmentGHSA-g3qh-qhp8-8f86 · GitHub CVSS 6.5
- 2026-08-02 02:27 UTCEPSS rescoreEPSS 0.2% · 10th percentile
Related CVEs(same vendor + same CWE)
Same vendor
10 shownredhat:RHSA-2026:6188
Frequently asked(5)
What is CVE-2026-3889?
When was the CVE record for CVE-2026-3889 published?
Is CVE-2026-3889 actively exploited?
What is the CVSS score of CVE-2026-3889?
How do I remediate CVE-2026-3889?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-3889
Is Your Infrastructure Affected by CVE-2026-3889?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.