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CVE-2021-35207

21
FAUCET Score

CVE-2021-35207 is a Cross-Site Scripting (XSS) vulnerability found in Zimbra Collaboration Suite versions 8.8 before Patch 23 and 9.0 before Patch 16. An attacker can exploit this by injecting malicious JavaScript into the loginErrorCode parameter of the Zimbra Web Client's login URL. This vulnerability has a CVSS score of 6.1 (Medium), indicating it can be exploited remotely with low complexity, requiring user interaction, and potentially leading to limited confidentiality and integrity impacts. While there is no public exploit code available (Metasploit, Nuclei, ExploitDB), it has garnered some community discussion and media coverage, with reports of the APT group Winter Vivern exploiting a Zimbra webmail flaw, though it's not confirmed if this specific CVE is the one being leveraged.

Impacted Technologies

VendorProductVersion(s)CPE
>= 8.8, < 8.8.15CPE matchmatch criteria
cpe:2.3:a:zimbra:collaboration:*:*:*:*:*:*:*:*
8.8.15CPE matchmatch criteria
cpe:2.3:a:zimbra:collaboration:8.8.15:-:*:*:*:*:*:*
8.8.15CPE matchmatch criteria
cpe:2.3:a:zimbra:collaboration:8.8.15:p1:*:*:*:*:*:*
8.8.15CPE matchmatch criteria
cpe:2.3:a:zimbra:collaboration:8.8.15:p10:*:*:*:*:*:*
8.8.15CPE matchmatch criteria
cpe:2.3:a:zimbra:collaboration:8.8.15:p11:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.27%
Probability of exploitation in next 30 days
EPSS Percentile
87.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0327 is in the 94th percentile among its peer group of 26,236 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

wiki.zimbra.com / wiki/Security_Center
Release NotesVendor Advisory
wiki.zimbra.com / wiki/Zimbra_Releases/8.8.15/P23
Vendor Advisory
wiki.zimbra.com / wiki/Zimbra_Releases/9.0.0/P16
Vendor Advisory
wiki.zimbra.com / wiki/Zimbra_Security_Advisories
Vendor Advisory