CVE-2026-45820

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory published 2026-07-22. NVD baseline CVSS 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

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

fflate through 0.8.2 is vulnerable to denial of service via an infinite loop in unzipSync(). A crafted ZIP archive with a central directory entry declaring compressed_size=0xFFFFFFFF (ZIP64 sentinel) but missing the required ZIP64 extra field tag 0x0001 causes z64e() to loop indefinitely due to out-of-bounds reads returning undefined, which coerces to 0, keeping the loop condition permanently true.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

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
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
20%
KEV
Not listed

Published

July 22, 2026

Last Modified

August 19, 2026

Advisory Details (1)

Auto-updated Jul 22, 2026
No patch confirmed yet.
generic

fflate/src/index.ts at f7873560ad229c22c4b23b06c6a3806ffde77569 · 101arrowz/fflate · GitHub

https://github.com/101arrowz/fflate/blob/f7873560ad229c22c4b23b06c6a3806ffde77569/src/index.ts#L2714

Vendor Advisories for CVE-2026-45820(1)

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

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
fflate—0.8.3—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 72× 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 149 total refreshes for this CVE.

  1. 2026-09-13 22:27 UTCEG score recompute
  2. 2026-09-13 16:47 UTCEPSS rescore
  3. 2026-09-12 20:56 UTCEG score recompute
  4. 2026-09-12 15:01 UTCEPSS rescore
  5. 2026-09-11 20:35 UTCEG score recompute
  6. 2026-09-11 14:53 UTCEPSS rescore
  7. 2026-09-11 09:37 UTCEPSS rescore
  8. 2026-09-10 21:45 UTCEG score recompute
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-09 09:19 UTCEG score recompute
  11. 2026-09-08 22:00 UTCEPSS rescore
  12. 2026-09-07 21:43 UTCEG score recompute
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-05 19:36 UTCEG score recompute
  15. 2026-09-05 07:17 UTCEG score recompute
  16. 2026-09-04 13:59 UTCEG score recompute
  17. 2026-09-04 05:06 UTCEPSS rescore
  18. 2026-09-02 14:12 UTCEPSS rescore
  19. 2026-09-01 23:42 UTCEG score recompute
  20. 2026-09-01 23:42 UTCGHSA enrichment
  21. 2026-09-01 13:54 UTCEPSS rescore
  22. 2026-08-31 00:09 UTCEG score recompute
  23. 2026-08-31 00:09 UTCGHSA enrichment
  24. 2026-08-30 19:17 UTCEPSS rescore
  25. 2026-08-30 12:45 UTCEG score recompute
Show 75 more
  1. 2026-08-30 12:45 UTCGHSA enrichment
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-30 00:57 UTCEG score recompute
  4. 2026-08-30 00:57 UTCGHSA enrichment
  5. 2026-08-28 21:41 UTCEPSS rescore
  6. 2026-08-27 22:58 UTCEG score recompute
  7. 2026-08-27 22:58 UTCGHSA enrichment
  8. 2026-08-27 14:25 UTCEPSS rescore
  9. 2026-08-27 11:33 UTCGHSA enrichment
  10. 2026-08-27 00:08 UTCEG score recompute
  11. 2026-08-27 00:08 UTCGHSA enrichment
  12. 2026-08-26 14:46 UTCEPSS rescore
  13. 2026-08-26 12:43 UTCGHSA enrichment
  14. 2026-08-26 01:11 UTCEG score recompute
  15. 2026-08-26 01:11 UTCGHSA enrichment
  16. 2026-08-25 13:49 UTCEPSS rescore
  17. 2026-08-25 13:46 UTCGHSA enrichment
  18. 2026-08-25 02:21 UTCGHSA enrichment
  19. 2026-08-24 14:55 UTCEG score recompute
  20. 2026-08-24 14:55 UTCGHSA enrichment
  21. 2026-08-24 03:30 UTCGHSA enrichment
  22. 2026-08-23 14:42 UTCGHSA enrichment
  23. 2026-08-23 03:18 UTCEG score recompute
  24. 2026-08-23 03:18 UTCGHSA enrichment
  25. 2026-08-23 00:19 UTCEPSS rescore
  26. 2026-08-22 15:53 UTCGHSA enrichment
  27. 2026-08-22 04:19 UTCEG score recompute
  28. 2026-08-22 04:19 UTCGHSA enrichment
  29. 2026-08-21 23:49 UTCEPSS rescore
  30. 2026-08-21 16:54 UTCEG score recompute
  31. 2026-08-21 16:54 UTCGHSA enrichment
  32. 2026-08-21 05:29 UTCEG score recompute
  33. 2026-08-21 05:29 UTCGHSA enrichment
  34. 2026-08-20 22:55 UTCEPSS rescore
  35. 2026-08-20 18:04 UTCGHSA enrichment
  36. 2026-08-20 06:40 UTCEG score recompute
  37. 2026-08-20 06:40 UTCGHSA enrichment
  38. 2026-08-19 19:15 UTCEG score recompute▲ 0.90
  39. 2026-08-19 19:15 UTCGHSA enrichment
  40. 2026-08-19 19:14 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
  41. 2026-08-19 17:04 UTCEPSS rescore
  42. 2026-08-18 19:12 UTCEG score recompute
  43. 2026-08-18 19:12 UTCGHSA enrichment
  44. 2026-08-18 13:48 UTCEPSS rescore
  45. 2026-08-17 13:47 UTCEPSS rescore
  46. 2026-08-17 13:02 UTCEG score recompute
  47. 2026-08-17 13:02 UTCGHSA enrichment
  48. 2026-08-16 14:56 UTCEPSS rescore
  49. 2026-08-16 12:37 UTCEG score recompute
  50. 2026-08-16 12:37 UTCGHSA enrichment
  51. 2026-08-16 02:14 UTCEPSS rescore
  52. 2026-08-15 12:13 UTCEG score recompute
  53. 2026-08-15 12:13 UTCGHSA enrichment
  54. 2026-08-15 01:30 UTCEPSS rescore
  55. 2026-08-14 11:48 UTCEG score recompute
  56. 2026-08-14 11:48 UTCGHSA enrichment
  57. 2026-08-13 22:00 UTCEPSS rescore
  58. 2026-08-13 11:24 UTCEG score recompute
  59. 2026-08-13 11:24 UTCGHSA enrichment
  60. 2026-08-12 13:51 UTCEPSS rescore
  61. 2026-08-12 11:00 UTCEG score recompute
  62. 2026-08-12 11:00 UTCGHSA enrichment
  63. 2026-08-11 10:35 UTCEG score recompute
  64. 2026-08-11 10:35 UTCGHSA enrichment
  65. 2026-08-11 00:00 UTCEPSS rescore
  66. 2026-08-10 10:10 UTCEG score recompute
  67. 2026-08-10 10:10 UTCGHSA enrichment
  68. 2026-08-09 13:46 UTCEPSS rescore
  69. 2026-08-09 09:46 UTCEG score recompute
  70. 2026-08-09 09:46 UTCGHSA enrichment
  71. 2026-08-08 16:37 UTCEPSS rescore
  72. 2026-08-08 09:22 UTCEG score recompute
  73. 2026-08-08 09:22 UTCGHSA enrichment
  74. 2026-08-07 08:57 UTCEG score recompute
  75. 2026-08-07 08:57 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-45820?
CVE-2026-45820 is a high vulnerability published on July 22, 2026. fflate through 0.8.2 is vulnerable to denial of service via an infinite loop in unzipSync(). A crafted ZIP archive with a central directory entry declaring compressed_size=0xFFFFFFFF (ZIP64 sentinel) but missing the required ZIP64 extra field tag 0x0001 causes z64e() to loop indefinitely due to…
When was CVE-2026-45820 disclosed?
CVE-2026-45820 was first published in the National Vulnerability Database on July 22, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45820 actively exploited?
CVE-2026-45820 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 79.8% of all scored CVEs.
What is the CVSS score of CVE-2026-45820?
CVE-2026-45820 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-45820?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45820, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-45820

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