Security readout for executives and security teams
Plain-English summary
EspoCRM 6.1.6 and earlier can store attacker-supplied script through avatar image handling. A logged-in attacker would need another user to view the affected content. The issue can expose sensitive browser-accessible data in the EspoCRM session context. The documented fix is EspoCRM 6.1.7.
Executive priority
Treat this as a moderate web application risk. It is not documented as actively exploited in the provided sources, but stored XSS can support account data exposure inside CRM workflows. Patch during the next regular security maintenance window, faster for externally reachable systems.
Technical view
CVE-2021-3539 is a persistent CWE-79 cross-site scripting flaw in EspoCRM avatar image processing. The CVSS 3.1 score is 6.3 with network access, low complexity, low privileges, and required user interaction. The impact is high confidentiality, low integrity, and no availability impact.
Likely exposure
Exposure is limited to EspoCRM deployments running version 6.1.6 or earlier, especially where users can upload avatar images and other users view them. The source bundle does not identify affected forks, hosted services, or downstream packages.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. Abuse would require an authenticated actor and user interaction, but persistence increases risk because the payload can remain in stored profile content until remediated.
Researcher notes
Evidence is concise: the CVE record and Rapid7 reference identify persistent XSS in user-supplied avatar image processing and the fix version. The bundle does not provide exploit details, patch diff, affected configuration nuance, or post-upgrade cleanup guidance.
Mitigation direction
- Upgrade EspoCRM deployments to version 6.1.7 or later.
- Check vendor guidance for handling existing uploaded avatar content.
- Limit avatar upload capability to trusted users until upgraded.
- Prioritize internet-facing or broadly accessible EspoCRM instances first.
Validation and detection
- Inventory all EspoCRM instances and confirm their running versions.
- Confirm no production instance remains on 6.1.6 or earlier.
- Review whether avatar uploads are enabled for non-admin users.
- After upgrade, verify avatar upload and display workflows still function safely.
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.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-3539 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N
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 vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N2.14.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.rapid7.com/blog/post/2021/07/27/multiple-open-source-web-app-vulnerabilities-fixed/CVE 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.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.