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Vulnerability · Published Jul 12, 2021 · Assigned by GitHub_M

CVE-2021-32679Filenames not escaped by default in controllers using DownloadResponse

Low 3.5

In plain English

A low-severity security flaw in security-advisories from nextcloud. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.4% (higher than 72% of all known vulnerabilities).

Severity (CVSS 3.1)3.5Low
Exploit odds (30 days)1.4%top 28.0% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

Nextcloud Server is a Nextcloud package that handles data storage. In versions prior to 19.0.13, 20.0.11, and 21.0.3, filenames where not escaped by default in controllers using `DownloadResponse`. When a user-supplied filename was passed unsanitized into a `DownloadResponse`, this could be used to trick users into downloading malicious files with a benign file extension. This would show in UI behaviours where Nextcloud applications would display a benign file extension (e.g. JPEG), but the file will actually be downloaded with an executable file extension. The vulnerability is patched in versions 19.0.13, 20.0.11, and 21.0.3. Administrators of Nextcloud instances do not have a workaround available, but developers of Nextcloud apps may manually escape the file name before passing it into `DownloadResponse`.

Affected products (as reported)

VendorProductVersions
nextcloud security-advisories < 19.0.13>= 20.0.0, < 20.0.11>= 21.0.0, < 21.0.3

Weakness: CWE-116 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

References