CVE-2026-26028

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

Score 6.1 from GitHub Security Advisory published 2026-05-26. NVD baseline CVSS 6.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.1
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.1Exploit: NoneExposed: 0

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

CryptPad is an end-to-end encrypted collaborative office suite. In versions prior to 2026.2.0, the HTML sanitizer in Diffmarked.js can be bypassed due to incomplete attribute filtering on restricted tags. The sanitizer validates only the src attribute of , , and elements, leaving all other attributes unchecked. As a result, an attacker can inject arbitrary HTML through srcdoc, completely defeating CryptPad's intended bounce sandboxing and enabling link injection or other interactive content within user-controlled documents. The root cause lies in how the sanitizer classifies and enforces tag restrictions: although it defines both forbidden and restricted tag lists, is treated as "restricted" rather than "forbidden." Enforcement then inspects only the src attribute, so pairing a benign blob: src with a malicious srcdoc results in unrestricted rendering. This issue has been fixed in version 2026.2.0.

CVSS v3
6.1
EG Score
6.1(medium)
EPSS
15.3%
KEV
Not listed

Published

May 20, 2026

Last Modified

May 21, 2026

Advisory Details (2)

Auto-updated Jun 13, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github.
github Patch Available🟡 PoC Available

Sanitizer Bypass in Diffmarked.js Allows Arbitrary HTML Injection Potentially Leading to XSS · Advisory · cryptpad/cryptpad · GitHub

https://github.com/cryptpad/cryptpad/security/advisories/GHSA-g2g4-47gv-p72v
github_release Patch Available

❄️ Winter release (2026.2.0)

Patch available: cryptpad/cryptpad 2026.2.0

https://github.com/cryptpad/cryptpad/releases/tag/2026.2.0

Vendor Advisories for CVE-2026-26028(1)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
npmcryptpad—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
cryptpad———

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 61× 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 140 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-26028?
CVE-2026-26028 is a medium vulnerability published on May 20, 2026. CryptPad is an end-to-end encrypted collaborative office suite. In versions prior to 2026.2.0, the HTML sanitizer in Diffmarked.js can be bypassed due to incomplete attribute filtering on restricted tags. The sanitizer validates only the src attribute of <iframe>, <video>, and <audio> elements,…
When was CVE-2026-26028 disclosed?
CVE-2026-26028 was first published in the National Vulnerability Database on May 20, 2026, with the most recent update on May 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-26028 actively exploited?
CVE-2026-26028 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 15.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-26028?
CVE-2026-26028 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-26028?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-26028, 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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