CVE-2023-35171Public exploitNetwork attack vector

Phishing redirects via unchecked unsupported-browser return URL

Published Jun 23, 2023 · Updated Nov 7, 2024

Open redirect in Nextcloud Server and Enterprise Server 26.0.0 through 26.0.1 allows remote authenticated users to reach attacker sites. UnsupportedBrowser.vue builds its Continue button target from a Base64-decoded redirect_url request parameter without restricting the destination to a local path. Exploitation requires an authenticated victim using an unsupported browser to open a crafted legitimate-domain URL and click the Continue button, enabling phishing through an attacker-controlled site.

CVSS severity4.1
Medium
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in Nextcloud Server and Enterprise Server 26.0.0 through 26.0.1 allows remote authenticated users to reach attacker sites. UnsupportedBrowser.vue builds its Continue button target from a Base64-decoded redirect_url request parameter without restricting the destination to a local path. Exploitation requires an authenticated victim using an unsupported browser to open a crafted legitimate-domain URL and click the Continue button, enabling phishing through an attacker-controlled site.

The record

CVE
CVE-2023-35171
Published
Jun 23, 2023
Updated
Nov 7, 2024
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-601, T1566.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 23, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 26.0.0, < 26.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Security Advisoriesversion=>= 26.0.0, < 26.0.2

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
T1566.002Spearphishing Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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