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CVE-2026-45278— Nextcloud: Open Redirect in user_oidc login flow via protocol-relative URL bypass

Quick assessment

Affected

nextcloud security-advisories

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Nextcloud user_oidc是德国Nextcloud公司的一个应用程序 Nextcloud user_oidc 6.1.0版本至8.2.2之前版本存在输入验证错误漏洞，该漏洞源于重定向处理不当，可能导致攻击者制作链接将用户重定向到其他网站。

CVSS 3.3 · Low EPSS 0.32% · P24 Updated Jun 02, 2026

Possible ATT&CK Techniques 1 AI

T1566.002 · Spearphishing Link

Affected Version Matrix 1

Vendor	Product	Version Range	Status
nextcloud	security-advisories	`>= 6.1.0, < 8.2.2`	affected

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I. Basic Information for CVE-2026-45278

Vulnerability Information

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Vulnerability Title

Nextcloud: Open Redirect in user_oidc login flow via protocol-relative URL bypass

Source: CVE Program / CVE List V5

Vulnerability Description

Nextcloud is an open source content collaboration platform. From version 6.1.0 to before version 8.2.2, an attacker can craft links that would redirect users to another website, when the victim uses the attackers link to log in via user OIDC. This issue has been patched in version 8.2.2.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Source: CVE Program / CVE List V5

Vulnerability Type

指向未可信站点的URL重定向(开放重定向)

Source: CVE Program / CVE List V5

Vulnerability Title

Nextcloud user_oidc 输入验证错误漏洞

Source: CNNVD (China National Vulnerability Database)

Vulnerability Description

Source: CNNVD (China National Vulnerability Database)

CVSS Information

N/A

Source: CNNVD (China National Vulnerability Database)

Vulnerability Type

N/A

Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
nextcloud	security-advisories	>= 6.1.0, < 8.2.2	-

II. Public POCs for CVE-2026-45278

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

No public POC found.

III. Intelligence Information for CVE-2026-45278

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Patches & Fixes for CVE-2026-45278 (1)

🔗 Improve check on redirect URL by julien-nc · Pull Request #1273 · nextcloud/user_oidc · GitHub x_refsource_MISC

Vendor Advisories for CVE-2026-45278 (1)

🔗 Open Redirect in user_oidc login flow via protocol-relative URL bypass · Advisory · nextcloud/security-advisories · GitHub Read full article x_refsource_CONFIRM

https://www.cve.org/CVERecord?id=CVE-2026-45278

Same Patch Batch · nextcloud · 2026-06-01 · 26 CVEs total

CVE-2026-45545	8.2 HIGH	Nextcloud: SQL Injection in Column Type Parameter Allows Arbitrary SQL Execution
CVE-2026-45156	8.1 HIGH	Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification
CVE-2026-45281	8.1 HIGH	Nextcloud: Cross-Account Calendar Takeover via Unauthorized Group-Member-Set Update
CVE-2026-45722	7.1 HIGH	Nextcloud: Tables app allows limited SQLi in ORDER BY with malicious sort order argument f
CVE-2026-45810	6.8 MEDIUM	Nextcloud: Propfind requests for file comments allowed to load comments for other files
CVE-2026-45267	6.5 MEDIUM	Nextcloud: Missing permission check for from submissions
CVE-2026-45275	6.5 MEDIUM	Nextcloud: Authorization bypass in approval feature allows unauthorized file sharing with
CVE-2026-45282	6.5 MEDIUM	Nextcloud: Logged-in user bypasses share password and download restrictions on Text attach
CVE-2026-45285	6.4 MEDIUM	Nextcloud: Hidden Public Link creation when sharing to a Team External Member
CVE-2026-45157	6.3 MEDIUM	Nextcloud: Valid share tokens allow to access tempory upload files of share owner
CVE-2026-45283	6.3 MEDIUM	Nextcloud: Files Lock app allows users to lock and unlock files of other users
CVE-2026-45691	5.9 MEDIUM	Nextcloud: Bypass of second factor authentication on DAV endpoints
CVE-2026-45690	5.9 MEDIUM	Nextcloud: Two-Factor Authentication Bypass via Pending Session Token Replay
CVE-2026-45543	5.3 MEDIUM	Nextcloud: Deleting a Forms collaborator share leaves uploaded response files accessible t
CVE-2026-45153	4.6 MEDIUM	Nextcloud: PIN bypass in PassCodeActivity via back button
CVE-2026-45284	4.6 MEDIUM	Nextcloud: Wrong condition in the User OIDC app's LdapService allowed deleted LDAP users t
CVE-2026-45279	4.4 MEDIUM	Nextcloud: Limited path traversal via template API if using `{lang}` in config
CVE-2026-45544	4.3 MEDIUM	Nextcloud: Information Disclosure of view filter metdata via Broken Sensitive Data Masking
CVE-2026-45286	4.3 MEDIUM	Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint
CVE-2026-45264	4.3 MEDIUM	Nextcloud: ACL Rename Permission Bypass in Team Folders Allows Unauthorized File Renames

Showing top 20 of 26 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: security-advisories

Same vendor: nextcloud

Same weakness: CWE-601