CVE-2026-53899

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2026-06-16. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 6.5Exploit: None knownExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

Firefox for iOS used partial domain matching when attaching cookies to PDF requests, allowing a malicious site on a suffix domain to receive cookies belonging to the target site. This vulnerability was fixed in Firefox for iOS 152.0.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
34
EG Risk 34/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity65% × 45%
Exploitation0% × 40%
Automatability30% × 15%
EPSS PROB
0.1%
EPSS %ILE
2nd
KEV
Not listed

Published

June 16, 2026

Last Modified

June 17, 2026

Advisory Details (2)

Auto-updated Jun 16, 2026
No fix on record yet.
generic

Security Vulnerabilities fixed in Firefox for iOS 152.0 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-56/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2042909

Vendor Advisories for CVE-2026-53899(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 25× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 177 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-53899?
CVE-2026-53899 is a medium vulnerability published on June 16, 2026. Firefox for iOS used partial domain matching when attaching cookies to PDF requests, allowing a malicious site on a suffix domain to receive cookies belonging to the target site. This vulnerability was fixed in Firefox for iOS 152.0.
When was CVE-2026-53899 disclosed?
CVE-2026-53899 was first published on June 16, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53899 actively exploited?
CVE-2026-53899 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (2nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-53899?
CVE-2026-53899 has a CVSS v3.1 base score of 6.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-53899?
No fix for CVE-2026-53899 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-53899 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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