CVE-2026-40033

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-05-26. a secondary CVSS source baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
8.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 8.8Exploit: NoneExposed: 0

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

FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdi_CacheToSurface that allows remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation clamps coordinates to UINT16_MAX but performs copy operations using unclamped cache entry dimensions, enabling malicious RDP servers to trigger large out-of-bounds writes and potentially achieve remote code execution or client crash.

CVSS v3
8.8
EG Score
8.8(medium)
EPSS
53.4%
KEV
Not listed

Published

May 26, 2026

Last Modified

July 16, 2026

Advisory Details (3)

Auto-updated Jun 2, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

FreeRDP RDPGFX CacheToSurface heap-buffer-overflow via clamped-rectangle validation bypass · Advisory · FreeRDP/FreeRDP · GitHub

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff
generic

FreeRDP - Heap-buffer-overflow in gdi_CacheToSurface via rectangle validation bypass | Advisories | VulnCheck

https://www.vulncheck.com/advisories/freerdp-heap-buffer-overflow-in-gdi-cachetosurface-via-rectangle-validation-bypass
github_commit

commit 23b36cd00ebf (FreeRDP/FreeRDP)

Fix landed in FreeRDP/FreeRDP commit 23b36cd00ebf — awaiting tagged release

https://github.com/FreeRDP/FreeRDP/commit/23b36cd00ebf0ccd97750fcdbc9aa2f362352da7

Vendor Advisories for CVE-2026-40033(2)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 50× 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 124 total refreshes for this CVE.

  1. 2026-07-20 17:08 UTCEPSS rescore
  2. 2026-07-19 07:52 UTCOSV refresh
  3. 2026-07-19 02:29 UTCEPSS rescore
  4. 2026-07-18 10:04 UTCEPSS rescore
  5. 2026-07-16 17:03 UTCEPSS rescore
  6. 2026-07-16 12:29 UTCNVD updateCVSS v4 → 8.7
  7. 2026-07-16 12:08 UTCMITRE cvelistV5CVSS v4 → 8.6
  8. 2026-07-15 16:57 UTCEPSS rescore
  9. 2026-07-15 16:57 UTCEPSS rescore
  10. 2026-07-15 02:25 UTCNVD updateCVSS v4 → 8.7
  11. 2026-07-15 02:00 UTCEPSS rescore
  12. 2026-07-15 01:21 UTCMITRE cvelistV5CVSS v4 → 8.6
  13. 2026-07-13 22:30 UTCEPSS rescore
  14. 2026-07-12 05:46 UTCEPSS rescore
  15. 2026-07-11 08:27 UTCEPSS rescore
  16. 2026-07-09 19:10 UTCEPSS rescore
  17. 2026-07-08 15:15 UTCEPSS rescore
  18. 2026-07-08 14:36 UTCNVD updateCVSS v4 → 8.7
  19. 2026-07-08 12:47 UTCMITRE cvelistV5CVSS v4 → 8.6
  20. 2026-07-07 13:46 UTCEPSS rescore
  21. 2026-07-06 16:27 UTCEPSS rescore
  22. 2026-07-06 16:27 UTCEPSS rescore
  23. 2026-07-06 02:23 UTCEPSS rescore
  24. 2026-07-06 02:23 UTCEPSS rescore
  25. 2026-07-05 02:30 UTCEPSS rescore
Show 75 more
  1. 2026-07-04 06:31 UTCEPSS rescore
  2. 2026-07-01 15:06 UTCEPSS rescore
  3. 2026-07-01 14:09 UTCGHSA enrichment
  4. 2026-06-30 23:22 UTCEPSS rescore
  5. 2026-06-30 04:33 UTCNVD updateCVSS v4 → 8.7
  6. 2026-06-29 14:59 UTCGHSA enrichment
  7. 2026-06-29 14:06 UTCEPSS rescore
  8. 2026-06-28 23:43 UTCGHSA enrichment
  9. 2026-06-28 14:07 UTCEPSS rescore
  10. 2026-06-28 09:15 UTCGHSA enrichment
  11. 2026-06-28 04:56 UTCEPSS rescore
  12. 2026-06-27 20:10 UTCGHSA enrichment
  13. 2026-06-27 07:07 UTCGHSA enrichment
  14. 2026-06-27 03:08 UTCEPSS rescore
  15. 2026-06-26 17:56 UTCGHSA enrichment
  16. 2026-06-26 02:52 UTCGHSA enrichment
  17. 2026-06-25 13:49 UTCEPSS rescore
  18. 2026-06-25 13:49 UTCEPSS rescore
  19. 2026-06-25 12:04 UTCGHSA enrichment
  20. 2026-06-24 14:05 UTCEPSS rescore
  21. 2026-06-23 21:33 UTCEPSS rescore
  22. 2026-06-22 14:25 UTCEPSS rescore
  23. 2026-06-22 14:25 UTCEPSS rescore
  24. 2026-06-21 14:56 UTCEPSS rescore
  25. 2026-06-21 14:56 UTCEPSS rescore
  26. 2026-06-21 01:59 UTCEPSS rescore
  27. 2026-06-19 19:25 UTCEPSS rescore
  28. 2026-06-18 17:52 UTCEPSS rescore
  29. 2026-06-18 17:52 UTCEPSS rescore
  30. 2026-06-17 19:25 UTCGHSA enrichment
  31. 2026-06-17 17:53 UTCEPSS rescore
  32. 2026-06-17 06:22 UTCGHSA enrichment
  33. 2026-06-16 17:52 UTCEPSS rescore
  34. 2026-06-16 17:19 UTCGHSA enrichment
  35. 2026-06-16 02:54 UTCGHSA enrichment
  36. 2026-06-15 17:49 UTCEPSS rescore
  37. 2026-06-15 13:51 UTCGHSA enrichment
  38. 2026-06-14 23:24 UTCGHSA enrichment
  39. 2026-06-14 10:21 UTCGHSA enrichment
  40. 2026-06-13 23:00 UTCEPSS rescore
  41. 2026-06-13 21:18 UTCGHSA enrichment
  42. 2026-06-13 03:28 UTCGHSA enrichment
  43. 2026-06-12 23:12 UTCEPSS rescore
  44. 2026-06-12 23:12 UTCEPSS rescore
  45. 2026-06-12 14:25 UTCGHSA enrichment
  46. 2026-06-12 01:23 UTCGHSA enrichment
  47. 2026-06-11 14:00 UTCEPSS rescore
  48. 2026-06-11 12:20 UTCGHSA enrichment
  49. 2026-06-10 23:17 UTCGHSA enrichment
  50. 2026-06-10 22:18 UTCEPSS rescore
  51. 2026-06-10 13:22 UTCEPSS rescore
  52. 2026-06-10 13:22 UTCEPSS rescore
  53. 2026-06-10 10:15 UTCGHSA enrichment
  54. 2026-06-09 21:12 UTCGHSA enrichment
  55. 2026-06-09 08:09 UTCGHSA enrichment
  56. 2026-06-08 19:06 UTCGHSA enrichment
  57. 2026-06-08 14:17 UTCEPSS rescore
  58. 2026-06-08 14:17 UTCEPSS rescore
  59. 2026-06-08 03:46 UTCGHSA enrichment
  60. 2026-06-07 15:25 UTCEPSS rescore
  61. 2026-06-07 15:25 UTCEPSS rescore
  62. 2026-06-07 15:25 UTCEPSS rescore
  63. 2026-06-07 14:44 UTCGHSA enrichment
  64. 2026-06-07 01:41 UTCGHSA enrichment
  65. 2026-06-06 13:47 UTCEPSS rescore
  66. 2026-06-06 13:47 UTCEPSS rescore
  67. 2026-06-06 12:38 UTCGHSA enrichment
  68. 2026-06-05 23:34 UTCGHSA enrichment
  69. 2026-06-05 22:47 UTCEPSS rescore
  70. 2026-06-05 22:47 UTCEPSS rescore
  71. 2026-06-05 10:30 UTCGHSA enrichment
  72. 2026-06-05 06:10 UTCEPSS rescore
  73. 2026-06-05 06:10 UTCEPSS rescore
  74. 2026-06-04 21:28 UTCGHSA enrichment
  75. 2026-06-04 08:25 UTCGHSA enrichment

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Frequently asked(5)

What is CVE-2026-40033?
CVE-2026-40033 is a high vulnerability published on May 26, 2026. FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdiCacheToSurface that allows remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation clamps coordinates to UINT16MAX but performs copy operations using unclamped cache entry…
When was CVE-2026-40033 disclosed?
CVE-2026-40033 was first published in the National Vulnerability Database on May 26, 2026, with the most recent update on July 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40033 actively exploited?
CVE-2026-40033 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 53.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40033?
CVE-2026-40033 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-40033?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40033, 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

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