CVE-2026-66729

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-27. a secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: Elevated riskExposed: 0

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

facil.io 0.6.0 through 0.7.6 contains an integer underflow vulnerability in the multipart MIME body parser that allows unauthenticated remote attackers to crash the server process by sending a crafted Content-Disposition header with an empty field name. Attackers can trigger a uint32_t wraparound in http_mime_parser.h causing an out-of-bounds memory read past the name pointer, resulting in a bus fault that crashes the handling worker with a single POST request.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

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%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
46%
KEV
Not listed

Published

July 27, 2026

Last Modified

July 31, 2026

Advisory Details (2)

Auto-updated Jul 27, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

facil.io 0.6.0 - 0.7.6 Integer Underflow DoS via Multipart MIME Body Parser | Advisories | VulnCheck

https://www.vulncheck.com/advisories/facil-io-integer-underflow-dos-via-multipart-mime-body-parser
generic🟡 PoC Available

GitHub - theopaid/Out-of-Bounds-Read-in-facil.io-MIME-Parser-leads-to-Server-Crash: Security Advisory: Out-of-Bounds Read in facil.io MIME Parser leads to Server crash · GitHub

https://github.com/theopaid/Out-of-Bounds-Read-in-facil.io-MIME-Parser-leads-to-Server-Crash

Vendor Advisories for CVE-2026-66729(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 20× in last 7d / 117× 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 134 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-66729?
CVE-2026-66729 is a high vulnerability published on July 27, 2026. facil.io 0.6.0 through 0.7.6 contains an integer underflow vulnerability in the multipart MIME body parser that allows unauthenticated remote attackers to crash the server process by sending a crafted Content-Disposition header with an empty field name. Attackers can trigger a uint32t wraparound in…
When was CVE-2026-66729 disclosed?
CVE-2026-66729 was first published in the National Vulnerability Database on July 27, 2026, with the most recent update on July 31, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66729 actively exploited?
CVE-2026-66729 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.2% of all scored CVEs.
What is the CVSS score of CVE-2026-66729?
CVE-2026-66729 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-66729?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66729, 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.

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