CVE-2025-27915

CRITICALNVD 5.49.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2025-10-07), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 5.4 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 4 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 4%CVSS: 5.4Exploit: cisa kev · ssvc active · public exploitExposed: 0

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

An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.

CVSS v3
5.4
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: 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
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
4%
EPSS %ILE
90%
KEV
⚠ Exploited

Published

March 12, 2025

Last Modified

November 4, 2025

Advisory Details (6)

Auto-updated Jun 13, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-27915
generic🔴 Active Exploitation

0day .ICS attack in the wild | StrikeReady Blog | StrikeReady

https://strikeready.com/blog/0day-ics-attack-in-the-wild/
generic

Zimbra Releases/9.0.0/P44 - Zimbra :: Tech Center

https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P44#Security_Fixes
generic

Zimbra Releases/10.1.5 - Zimbra :: Tech Center

https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.5#Security_Fixes
generic

Zimbra Releases/10.0.13 - Zimbra :: Tech Center

https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.13#Security_Fixes
generic🔴 Active Exploitation

Security Center - Zimbra :: Tech Center

https://wiki.zimbra.com/wiki/Security_Center

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 63× in last 7d / 248× 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 576 total refreshes for this CVE.

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

Publicly available exploits

(1 reference)

Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Nucleihttp/cves/2025/CVE-2025-27915.yaml
    First seen Jan 1, 2025

    Zimbra - Cross-Site Scripting via ICS Files

    Open source ↗

Frequently asked(6)

What is CVE-2025-27915?
CVE-2025-27915 is a critical vulnerability published on March 12, 2025. An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its…
When was CVE-2025-27915 disclosed?
CVE-2025-27915 was first published in the National Vulnerability Database on March 12, 2025, with the most recent update on November 4, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-27915 actively exploited?
Yes. CISA added CVE-2025-27915 to the Known Exploited Vulnerabilities catalog on October 7, 2025, affecting Synacor Zimbra Collaboration Suite (ZCS). KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2025-27915?
CVE-2025-27915 has a CVSS v3 base score of 5.4 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2025-27915?
CVE-2025-27915 affects Synacor Zimbra Collaboration Suite (ZCS). The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2025-27915?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-27915, 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

Explore the affected products and dependency analysis for CVE-2025-27915

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