Security readout for executives and security teams
Plain-English summary
An authenticated Nextcloud user could create mail aliases for other users in Nextcloud Mail before 1.9.5. This could enable impersonation or misrouting of mail inside an organization. The bundle does not provide CVSS scoring, so urgency depends on whether vulnerable Nextcloud Mail versions are deployed.
Executive priority
Treat this as a targeted access-control remediation if Nextcloud Mail is deployed. Prioritize upgrade and alias review, especially where internal mail identity is sensitive. Do not escalate as active exploitation based on the provided evidence.
Technical view
CVE-2021-22896 is a CWE-862 improper access control issue in Nextcloud Mail. A missing permission check allowed authenticated users to create mail aliases for other users. The provided sources identify Nextcloud Mail before 1.9.5 as affected and 1.9.5 as the fixed release.
Likely exposure
Exposure is likely limited to Nextcloud environments running the Mail app before version 1.9.5. Systems without Nextcloud Mail, or already on 1.9.5 or later, are not indicated as affected by the bundle.
Exploitation context
The issue requires authenticated access. The source bundle does not report public exploitation, and KEV status is false. No exploitability details should be assumed beyond the documented ability to create aliases for other users.
Researcher notes
Evidence is clear on the affected component, bug class, authenticated precondition, and fixed version. The bundle lacks CVSS details, exploit telemetry, and detailed environmental impact, so risk scoring should be refined using local deployment context.
Mitigation direction
- Upgrade Nextcloud Mail to version 1.9.5 or later.
- Review the Nextcloud security advisory and release notes for vendor guidance.
- Audit existing mail aliases for unexpected or unauthorized entries.
- If upgrade is delayed, check vendor guidance for supported compensating controls.
Validation and detection
- Inventory Nextcloud instances using the Mail app.
- Confirm installed Nextcloud Mail versions are 1.9.5 or later.
- Review alias records for ownership mismatches or unauthorized additions.
- Check administrative logs for alias changes by unexpected authenticated users.
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.
CWE-862: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. 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-2021-22896 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://hackerone.com/reports/1129996CVE reference · x_refsource_MISC
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-jmgp-77jq-fjp3CVE reference · x_refsource_MISC
- https://github.com/nextcloud/mail/pull/4864CVE reference · x_refsource_MISC
- https://github.com/nextcloud/mail/releases/tag/v1.9.5CVE 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.
Missing Authorization
Missing Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.