CVE-2026-35539

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 83% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
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.

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. XSS exists because of insufficient HTML attachment sanitization in preview mode. A victim must preview a text/html attachment.

CVSS v3
6.1
EG Score
6.1(medium)
EG Risk
28(Track)
EG Risk 28/100SSVC: 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
Severity61% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
16.6%
KEV
Not listed

Published

April 3, 2026

Last Modified

April 7, 2026

References (7)

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
roundcube/roundcubemail1.7-beta ... 1.7-rc4 (6 versions)1.7-rc5—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 40× 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.

  1. 2026-07-23 03:10 UTCEG score recompute
  2. 2026-07-22 14:08 UTCEPSS rescore
  3. 2026-07-21 15:24 UTCEPSS rescore
  4. 2026-07-20 17:08 UTCEPSS rescore
  5. 2026-07-19 14:31 UTCEPSS rescore
  6. 2026-07-19 02:29 UTCEPSS rescore
  7. 2026-07-18 10:04 UTCEPSS rescore
  8. 2026-07-17 03:24 UTCOSV refresh
  9. 2026-07-16 17:03 UTCEPSS rescore
  10. 2026-07-15 16:57 UTCEPSS rescore
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  20. 2026-07-07 13:46 UTCEPSS rescore
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  1. 2026-07-04 06:31 UTCEPSS rescore
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  3. 2026-06-30 23:22 UTCEPSS rescore
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  8. 2026-06-28 04:56 UTCEPSS rescore
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  18. 2026-06-21 14:56 UTCEPSS rescore
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  20. 2026-06-21 01:59 UTCEPSS rescore
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  23. 2026-06-18 17:52 UTCEPSS rescore
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  25. 2026-06-17 17:53 UTCEPSS rescore
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  27. 2026-06-15 17:49 UTCEPSS rescore
  28. 2026-06-14 23:18 UTCEPSS rescore
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  30. 2026-06-12 23:12 UTCEPSS rescore
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  35. 2026-06-08 14:17 UTCEPSS rescore
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  37. 2026-06-07 15:25 UTCEPSS rescore
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  40. 2026-06-06 13:47 UTCEPSS rescore
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  42. 2026-06-05 22:47 UTCEPSS rescore
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  44. 2026-06-05 06:10 UTCEPSS rescore
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  46. 2026-06-04 13:12 UTCEPSS rescore
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  48. 2026-06-02 20:13 UTCEPSS rescore
  49. 2026-06-01 13:52 UTCEPSS rescore
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  51. 2026-06-01 13:51 UTCEPSS rescore
  52. 2026-05-31 22:30 UTCEPSS rescore
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  54. 2026-05-31 00:16 UTCEPSS rescore
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  57. 2026-05-29 13:44 UTCEPSS rescore
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  59. 2026-05-28 13:44 UTCEPSS rescore
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  68. 2026-05-20 22:38 UTCEPSS rescore
  69. 2026-05-20 22:38 UTCEPSS rescore
  70. 2026-05-20 19:18 UTCEG score recompute
  71. 2026-05-20 11:22 UTCEPSS rescore
  72. 2026-05-20 11:22 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-35539?
CVE-2026-35539 is a medium vulnerability published on April 3, 2026. An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. XSS exists because of insufficient HTML attachment sanitization in preview mode. A victim must preview a text/html attachment.
When was CVE-2026-35539 disclosed?
CVE-2026-35539 was first published in the National Vulnerability Database on April 3, 2026, with the most recent update on April 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-35539 actively exploited?
CVE-2026-35539 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 16.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-35539?
CVE-2026-35539 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-35539?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-35539, 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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