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Fencer Vulns
medium 4.1

CVE-2023-35171 json

Nextcloud Server vulnerable to open redirect on "Unsupported browser" warning

published 2023-06-23 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-39175

cvss
4.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

NextCloud Server and NextCloud Enterprise Server provide file storage for Nextcloud, a self-hosted productivity platform. Starting in version 26.0.0 and prior to version 26.0.2, an attacker could supply a URL that redirects an unsuspecting victim from a legitimate domain to an attacker's site. Nextcloud Server and Nextcloud Enterprise Server 26.0.2 contain a patch for this issue. No known workarounds are available.

Patch / fix

  • nextcloud nextcloud_server 26.0.2

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-35171 updated cvss 4.1

NextCloud: Open redirect on "Unsupported browser" warning

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/nextcloud/security-advisories/security/advisories/GHSA-h353-vvwv-j2r4 referenced PoC, tagged "exploit" by a source, unverified
  • hackerone.com https://hackerone.com/reports/1977222 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

  • nextcloud security-advisories

Classification

Weakness
  • CWE-601 URL Redirection to Untrusted Site

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.