CVE-2026-78209

HIGHPre-NVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

Score 8.2 from GitHub Security Advisory (severity: HIGH) published 2026-08-24. A secondary CVSS source baseline 8.2; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
8.2EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 8.2Exploit: None knownExposed services: Not assessed

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

exceljs through 4.4.0 fails to neutralize leading equals, plus, minus, or at signs in cell values written to CSV output. Attackers who can influence exported cell values can inject formulas that execute when the CSV file is opened in a spreadsheet application, potentially exfiltrating data or performing other malicious actions.

CVSS v3
8.2
EG Score
8.2HIGHmedium confidence
EG Risk
37
EG Risk 37/100CISA SSVC

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
Severity82% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
EPSS PROB
0.4%
EPSS %ILE
33rd
KEV
Not listed

CISA SSVCTrack at every mission impact level.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 24, 2026

Last Modified

August 31, 2026

Advisory Details (4)

Auto-updated Aug 24, 2026
No fix on record yet. Sources: github.
generic

exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values | Advisories | VulnCheck

https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values
generic

exceljs/lib/csv/csv.js at v4.4.0 · exceljs/exceljs · GitHub

https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182
githubMentions a patch (unverified)

CSV Formula Injection in exceljs via `CSV.write()` · Advisory · mateocallec/exceljs-hardened · GitHub

https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw
generic

GitHub - exceljs/exceljs: Excel Workbook Manager · GitHub

https://github.com/exceljs/exceljs

Vendor Advisories for CVE-2026-78209(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 23× in last 7d / 110× 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 189 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-78209?
CVE-2026-78209 is a high vulnerability published on August 24, 2026. exceljs through 4.4.0 fails to neutralize leading equals, plus, minus, or at signs in cell values written to CSV output. Attackers who can influence exported cell values can inject formulas that execute when the CSV file is opened in a spreadsheet application, potentially exfiltrating data or…
When was CVE-2026-78209 disclosed?
CVE-2026-78209 was first published on August 24, 2026, with the most recent update on August 31, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-78209 actively exploited?
CVE-2026-78209 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (33rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-78209?
CVE-2026-78209 has a CVSS base score of 8.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-78209?
No fix for CVE-2026-78209 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-2026-78209 are linked in the Vendor Advisories panel on this page.

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