CVE-2023-25820 [Medium] | Security Vulnerability in Nextcloud Server

Nextcloud Server is the file server software for Nextcloud, a self-hosted productivity platform, and Nextcloud Enterprise Server is the enterprise version of the file server software. In Nextcloud Server versions 25.0.x prior to 25.0.5 and versions 24.0.x prior to 24.0.10 as well as Nextcloud Enterprise Server versions 25.0.x prior to 25.0.4, 24.0.x prior to 24.0.10, 23.0.x prior to 23.0.12.5, 22.x prior to 22.2.0.10, and 21.x prior to 21.0.9.10, when an attacker gets access to an already logged in user session they can then brute force the password on the confirmation endpoint. Nextcloud Server should upgraded to 24.0.10 or 25.0.4 and Nextcloud Enterprise Server should upgraded to 21.0.9.10, 22.2.10.10, 23.0.12.5, 24.0.10, or 25.0.4 to receive a patch. No known workarounds are available.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.03%	0.24%	+0.20%
2	2026-03-24	0.17%	0.03%	-0.14%
3	2026-03-23	—	0.17%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.03%

0.24%

+0.20%

2026-03-24

0.17%

0.03%

-0.14%

2026-03-23

—

0.17%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.2	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	0.8	3.4	[email protected]
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.2

3.1

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

0.8

3.4

[email protected]

7.8

3.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

Affected software / configurations for CVE-2023-25820

Vendor	Product	Version	Raw CPE
nextcloud	nextcloud_server	>= 21.0.0, < 21.0.9	cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*
nextcloud	nextcloud_server	>= 22.2.0, < 22.2.10.10	cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*
nextcloud	nextcloud_server	>= 23.0.0, < 23.0.12.5	cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*
nextcloud	nextcloud_server	>= 24.0.0, < 24.0.10	cpe:2.3:a:nextcloud:nextcloud_server::::::::
nextcloud	nextcloud_server	>= 24.0.0, < 24.0.10	cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*
nextcloud	nextcloud_server	>= 25.0.0, < 25.0.4	cpe:2.3:a:nextcloud:nextcloud_server::::::::
nextcloud	nextcloud_server	>= 25.0.0, < 25.0.4	cpe:2.3:a:nextcloud:nextcloud_server:::::enterprise:::*

References for CVE-2023-25820

URL	Tags
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-36g6-wjx2-333x	Vendor Advisory
https://github.com/nextcloud/server/pull/36489	Patch
https://hackerone.com/reports/1842114	Third Party Advisory

URL

CVE-2023-25820 | Nextcloud Server and Enterprise Server missing brute force protection on password confirmation modal

Exploit prediction scoring system (EPSS) score for CVE-2023-25820

Common vulnerability scoring system (CVSS) metrics for CVE-2023-25820

Weakness enumeration for CVE-2023-25820

Affected software / configurations for CVE-2023-25820

References for CVE-2023-25820