CVE-2026-40395

MEDIUMNVD 4.04.0—
EchelonGraph scoreMEDIUM confidence

Score 4.0 from GitHub Security Advisory published 2026-04-12. NVD baseline CVSS 4.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
4.0
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.0Exploit: NoneExposed: 0

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

Varnish Enterprise before 6.0.16r12 allows a "workspace overflow" denial of service (daemon panic) for shared VCL. The headerplus.write_req0() function from vmod_headerplus updates the underlying req0, which is normally the original read-only request from which req is derived (readable and writable from VCL). This is useful in the active VCL, after amending req, to prepare a refined req0 before switching to a different VCL with the return (vcl()) action. This is for example how the Varnish Controller operates shared VCL deployments. If the amended req contained too many header fields for req0, this would have resulted in a workspace overflow that would in turn trigger a panic and crash the Varnish Enterprise server. This could be used as a Denial of Service attack vector by malicious clients.

CVSS v3
4.0
EG Score
4.0(medium)
EG Risk
18(Track)
EG Risk 18/100SSVC: 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
Severity40% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
14.7%
KEV
Not listed

Published

April 12, 2026

Last Modified

April 17, 2026

References (1)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 37× 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 102 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-40395?
CVE-2026-40395 is a medium vulnerability published on April 12, 2026. Varnish Enterprise before 6.0.16r12 allows a "workspace overflow" denial of service (daemon panic) for shared VCL. The headerplus.writereq0() function from vmodheaderplus updates the underlying req0, which is normally the original read-only request from which req is derived (readable and writable…
When was CVE-2026-40395 disclosed?
CVE-2026-40395 was first published in the National Vulnerability Database on April 12, 2026, with the most recent update on April 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40395 actively exploited?
CVE-2026-40395 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 14.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40395?
CVE-2026-40395 has a CVSS v3 base score of 4.0 (NVD).
How do I remediate CVE-2026-40395?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40395, 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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