Security readout for executives and security teams
Plain-English summary
A vulnerable Nextcloud Desktop Client installer could run an attacker-placed uninstaller file from a writable system location with administrative privileges. This is a local privilege escalation risk on affected Windows endpoints, not a remote server compromise. The vendor-fixed version is 3.3.0.
Executive priority
Prioritize remediation on managed Windows endpoints where users have local access and software installs occur with administrator privileges. The impact can be full local compromise, but the attack is not described as remotely exploitable.
Technical view
CVE-2021-37617 is CWE-426 untrusted search path behavior in Nextcloud Desktop Client versions 3.0.3 through 3.2.4. During installation, the client looks for Uninstall.exe in a regular-user-writable folder and may execute it with administrator rights. The issue is fixed in 3.3.0.
Likely exposure
Exposure is most likely on Windows workstations with Nextcloud Desktop Client 3.0.3 through 3.2.4, especially where regular users can create files in C:\ and the client is installed or upgraded with administrative privileges.
Exploitation context
The sources describe local privilege escalation requiring a malicious local user and an installation action. KEV is false, and the provided sources do not report active exploitation in the wild or remote exploitation.
Researcher notes
The vendor advisory, CVE record, HackerOne report, and linked desktop pull request align on affected versions, root cause, workaround, and fixed release. Evidence in the bundle does not support claims of active exploitation or broader affected products.
Mitigation direction
- Upgrade Nextcloud Desktop Client to version 3.3.0 or later.
- Do not allow untrusted users to create content in C:\.
- Verify there is no unexpected C:\Uninstall.exe file on affected systems.
- Check vendor guidance before using additional compensating controls.
Validation and detection
- Inventory Windows endpoints for Nextcloud Desktop Client versions 3.0.3 through 3.2.4.
- Confirm upgraded endpoints report version 3.3.0 or later.
- Review C:\ permissions for regular-user file creation rights.
- Check whether C:\Uninstall.exe exists and investigate if present.
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-426: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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-2021-37617 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
- High
- CVSS
- 7.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
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:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H1.35.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-6q2w-v879-q24vCVE reference · x_refsource_CONFIRM
- https://github.com/nextcloud/desktop/pull/3497CVE reference · x_refsource_MISC
- https://hackerone.com/reports/1240749CVE 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.
Untrusted Search Path
Untrusted Search Path represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.