Page generated: 11 Nov 2026, 04:45 UTC
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CVE-2025-66376

Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.

CVSS 7.2 (HIGH) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.2/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 7.2: +1.08
  • Fresh EPSS: 20.23%: +0.10

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Sources: 19 documents and public datasets.

Hype components

Headline sample (25%)
0/100
Press, 30 days (60%)
0/100
Grounded branding (15%)
0/100
HYPE TOTAL0/100

Sources and documents

The Hacker News
Press · 20 Aug 2026, 07:00 · Attackers Exploit Zimbra SNMP Flaw for Unauthenticated Remote Code Execution - The Hacker News
Computer Weekly
Press · 29 Jul 2026, 07:00 · Laundry Bear pivots to new exploit days after Zimbra alert - Computer Weekly
Industrial Cyber
Press · 28 Jul 2026, 07:00 · Russian hacker group Laundry Bear exploits Zimbra zero-click flaw to target Western government, critical infrastructure - Industrial Cyber
Check Point Research
Press · 27 Jul 2026, 07:00 · 27th July – Threat Intelligence Report - Check Point Research
SOCRadar
Press · 24 Jul 2026, 07:00 · CVE-2025-66376: Russian APT Exploits Zimbra Zero-Day - SOCRadar
See all 19 source documents
Help Net Security
Press · 24 Jul 2026, 07:00 · Russian hackers exploit unpatched Zimbra servers to steal emails - Help Net Security
Korben
Press · 24 Jul 2026, 07:00 · Zimbra out of date? A Russian APT may already be reading your emails - Korben
Pasquale Pillitteri
Press · 24 Jul 2026, 07:00 · Zimbra Zero-Day: LAUNDRY BEAR Steals 90 Days of Email - Pasquale Pillitteri
The Register
Press · 23 Jul 2026, 07:00 · Year-long Russian attacks infect users as soon as they look at an email - The Register
The Hacker News
Press · 23 Jul 2026, 07:00 · Russian Espionage Group Exploited Zimbra Zero-Day to Steal Mail and 2FA Codes - The Hacker News
eSecurity Planet
Press · 23 Jul 2026, 07:00 · Russian TA488 Exploits Zimbra CVE-2025-66376 to Target Government Mail Servers - eSecurity Planet
Security Affairs
Press · 10 Jul 2026, 07:00 · Update Now: Critical Zimbra Classic Web Client Flaw Could Expose Mailboxes - Security Affairs
The Hacker News
Press · 21 Apr 2026, 07:00 · CISA Adds 8 Exploited Flaws to KEV, Sets April-May 2026 Federal Deadlines - The Hacker News
SC Media
Press · 20 Mar 2026, 07:00 · Russian APT weaponizes critical Zimbra bug in Ukraine-targeted intrusions - SC Media
BleepingComputer
Press · 19 Mar 2026, 07:00 · Russian hackers exploit Zimbra flaw in Ukrainian govt attacks - BleepingComputer
SecurityWeek
Press · 19 Mar 2026, 07:00 · Russian APT Exploits Zimbra Vulnerability Against Ukraine - SecurityWeek
Security Affairs
Press · 19 Mar 2026, 07:00 · Russian APT targets Ukraine via Zimbra XSS flaw CVE-2025-66376 - Security Affairs
The Hacker News
Press · 19 Mar 2026, 07:00 · CISA Warns of Zimbra, SharePoint Flaw Exploits; Cisco Zero-Day Hit in Ransomware Attacks - The Hacker News
BleepingComputer
Press · 18 Mar 2026, 07:00 · CISA orders feds to patch Zimbra XSS flaw exploited in attacks - BleepingComputer

Score evolution

● Hype   ● Reality

Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.

First record: hype 0.0 · reality 8.2 (2026-11-02 15:14). The curve appears once the score changes.

Public exploit evidence

0

Public exploit entries / repo candidates

Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.

Evidence in context

Confidence in exploitation evidence
Exploitation recorded
Priority basis
Recorded exploitation; CVSS 7.2; EPSS 20.2%
Attention, last 30 days
0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential
network access, no prior privileges, no user interaction.
Observed activity
Exploitation recorded in CISA KEV.
Known scale
Not quantified.
Evidence confidence basis
Trusted exploitation confirmation

Score evaluated: 2026-11-05 13:59:45.560576+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
Published
05 Jan 2026, 00:00
Added to the CISA KEV catalog
18 Mar 2026, 00:00
First press mention
18 Mar 2026, 07:00
Latest press mention
20 Aug 2026, 07:00
Score calculated
05 Nov 2026, 13:59