CVE-2026-41431

HIGHNVD 8.08.0
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This high-severity CVE scores 8.0 under NVD CVSS v3. EPSS exploit probability: 0.2% (9th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
Elevated

Also known asEUVD-2026-29119 (ENISA EUVD)Source: ENISA EUVD

8.0EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 8.0Exploit: No code on recordExposed services: Not assessed

The CVE record names the fixed release — apply it.

Zen is a firefox-based browser. Prior to 1.19.9b, Zen Browser ships a Mozilla Application Resource (MAR) updater (org.mozilla.updater) that has had all MAR signature verification stripped from the Firefox codebase it was forked from. The MAR files served to users contain zero cryptographic signatures, and the updater binary contains zero cryptographic verification code. This eliminates the defense-in-depth that MAR signing provides. If the update server or GitHub release pipeline is compromised, arbitrary unsigned code can be delivered to all Zen users via the auto-update mechanism. This vulnerability is fixed in 1.19.9b.

CVSS v3
8.0
EG Score
8.0HIGHmedium confidence
EG Risk
52
EG Risk 52/100

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)
Severity80% × 45%
Impact severity (EG Severity): CVSS 8.0 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (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: The CVE record names the fixed release. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.2%
EPSS %ILE
9th
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 (8.0): severity, escalated by confirmed exploitation. This CVE's 8.0 is its impact severity (EG Severity), not escalated.

EG Severity
8.0 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). 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, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 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 low, Track* at medium and Attend at high mission impact.

The CVE record names the fixed release. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (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)14 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 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

May 11, 2026

Last Modified

October 26, 2026

Advisory Details (2)

Auto-updated May 11, 2026
Fix named in the CVE record. Sources: github.
GitHub advisoryMentions a patch (unverified)

Zen Browser MAR updater ships with signature verification removed — unsigned updates accepted · Advisory · zen-browser/desktop · GitHub

https://github.com/zen-browser/desktop/security/advisories/GHSA-qpj9-m8jc-mw6q
Web page

Merge commit from fork · zen-browser/desktop@270db6d · GitHub

https://github.com/zen-browser/desktop/commit/270db6d6713d2c6c14d9df0b4bc7662843d3d54e

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 38× 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 199 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 99 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  2. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  3. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  4. 2026-10-26 18:34 UTCEG score recompute
  5. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  6. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  7. 2026-10-25 14:30 UTCEG score recompute
  8. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  9. 2026-10-24 06:55 UTCEG score recompute
  10. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  11. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  12. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  13. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  14. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  15. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  16. 2026-10-18 03:41 UTCEG score recompute
  17. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  18. 2026-10-17 14:36 UTCEG score recompute
  19. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  20. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  21. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  22. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  23. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  24. 2026-10-12 16:08 UTCEG score recompute
  25. 2026-10-11 19:50 UTCEG score recompute
Show 75 more
  1. 2026-10-11 17:04 UTCEG score recompute
  2. 2026-10-11 14:30 UTCEG score recompute
  3. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  4. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  5. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  6. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  7. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  8. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  9. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  10. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  11. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  12. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  13. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  14. 2026-09-30 06:58 UTCOSV refresh
  15. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  16. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  17. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  18. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  19. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  20. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  21. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  22. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  23. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  24. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  25. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  26. 2026-09-11 12:23 UTCOSV refresh
  27. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  28. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  29. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  30. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  31. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  32. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  33. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  34. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  35. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  36. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  37. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  38. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  39. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  40. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  41. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  42. 2026-08-23 18:38 UTCEG score recompute
  43. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  44. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  45. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  46. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  47. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  48. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  49. 2026-08-17 11:10 UTCEG score recompute
  50. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  51. 2026-08-16 04:25 UTCEG score recompute
  52. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  53. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  54. 2026-08-14 02:58 UTCEG score recompute
  55. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  56. 2026-08-12 16:30 UTCEG score recompute
  57. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  58. 2026-08-11 15:47 UTCEG score recompute
  59. 2026-08-11 13:43 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  60. 2026-08-11 01:10 UTCEG score recompute
  61. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  62. 2026-08-09 14:36 UTCEG score recompute
  63. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  64. 2026-08-09 02:15 UTCEG score recompute
  65. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  66. 2026-08-08 02:21 UTCEG score recompute
  67. 2026-08-07 01:37 UTCEG score recompute
  68. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  69. 2026-08-05 21:58 UTCEG score recompute
  70. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  71. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  72. 2026-08-04 10:38 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  73. 2026-08-03 19:26 UTCEG score recompute
  74. 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  75. 2026-08-02 14:28 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-41431?
CVE-2026-41431 is a high-severity vulnerability; its CVE record was published on May 11, 2026. Zen is a firefox-based browser. Prior to 1.19.9b, Zen Browser ships a Mozilla Application Resource (MAR) updater (org.mozilla.updater) that has had all MAR signature verification stripped from the Firefox codebase it was forked from. The MAR files served to users contain zero cryptographic…
When was the CVE record for CVE-2026-41431 published?
The CVE record for CVE-2026-41431 was published on May 11, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-41431 actively exploited?
CVE-2026-41431 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (9th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-41431?
CVE-2026-41431 has a CVSS v3 base score of 8.0 (NVD).
How do I remediate CVE-2026-41431?
The CVE record for CVE-2026-41431 names the fix: "This vulnerability is fixed in 1.19.9b."

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