Security readout for executives and security teams
Plain-English summary
CVE-2021-35207 is a cross-site scripting issue in the Zimbra Web Client login page. A crafted login URL can make a user's browser run attacker-supplied JavaScript. This matters most where Zimbra login pages are reachable by employees, partners, or the internet.
Executive priority
Prioritize remediation for internet-facing Zimbra login portals because this affects the authentication surface. Urgency is lower than confirmed exploited remote code execution, but patching should not wait for routine maintenance if exposed users are likely to receive crafted links.
Technical view
Zimbra Collaboration Suite 8.8 before 8.8.15 Patch 23 and 9.0 before 9.0.0 Patch 16 are affected. The login component fails to safely handle executable JavaScript supplied through the loginErrorCode URL parameter, enabling XSS in the Zimbra Web Client.
Likely exposure
Exposure is likely for organizations running affected Zimbra Collaboration Suite versions with the Web Client login page accessible. Internet-facing mail portals increase phishing and credential-risk relevance, but the source bundle does not provide scan prevalence or affected deployment counts.
Exploitation context
The provided sources describe the vulnerability but do not cite active exploitation. CISA KEV status is false in the bundle. Treat exploitation as plausible through social engineering or crafted links, but do not claim confirmed exploitation from these sources.
Researcher notes
The record lacks CVSS, CWE, and detailed exploit prerequisites. Analysis should stay scoped to reflected or parameter-driven XSS in the login component. Validate patch state through Zimbra version evidence, not only package names or banner assumptions.
Mitigation direction
- Upgrade Zimbra 8.8 deployments to 8.8.15 Patch 23 or later.
- Upgrade Zimbra 9.0 deployments to 9.0.0 Patch 16 or later.
- Review Zimbra Security Advisories for supported-version guidance.
- If patching is delayed, check Zimbra Security Center for vendor-supported interim guidance.
Validation and detection
- Inventory Zimbra Collaboration Suite versions and patch levels.
- Confirm Web Client login exposure for affected systems.
- Verify affected systems are at or beyond the named Zimbra patch levels.
- Review web access logs for suspicious login URLs containing loginErrorCode.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-35207 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesCVE reference · x_refsource_MISC
- https://wiki.zimbra.com/wiki/Security_CenterCVE reference · x_refsource_MISC
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16CVE reference · x_refsource_MISC
- https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.