CVE-2020-26255 [Medium] | File Upload / RCE in Kirby

Kirby is a CMS. In Kirby CMS (getkirby/cms) before version 3.4.5, and Kirby Panel before version 2.5.14 , an editor with full access to the Kirby Panel can upload a PHP .phar file and execute it on the server. This vulnerability is critical if you might have potential attackers in your group of authenticated Panel users, as they can gain access to the server with such a Phar file. Visitors without Panel access *cannot* use this attack vector. The problem has been patched in Kirby 2.5.14 and Kirby 3.4.5. Please update to one of these or a later version to fix the vulnerability. Note: Kirby 2 reaches end of life on December 31, 2020. We therefore recommend to upgrade your Kirby 2 sites to Kirby 3. If you cannot upgrade, we still recommend to update to Kirby 2.5.14.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	1.11%	1.47%	+0.36%
2	2025-05-22	1.02%	1.11%	+0.09%
3	2025-05-01	—	1.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

1.11%

1.47%

+0.36%

2025-05-22

1.02%

1.11%

+0.09%

2025-05-01

—

1.02%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
6.8	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. 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:H) They need powerful rights—admin, root, or similar—before this pays off. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	2.3	4.0	[email protected]
9.1	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. 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:H) They need powerful rights—admin, root, or similar—before this pays off. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. 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.	2.3	6.0	[email protected]
6.5	2.0	MEDIUM	`AV:N/AC:L/Au:S/C:P/I:P/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:S) A single authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	8.0	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

6.8

3.1

MEDIUM

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:H): They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

2.3

4.0

[email protected]

9.1

3.1

CRITICAL

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:H): They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
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.

2.3

6.0

[email protected]

6.5

2.0

MEDIUM

AV:N/AC:L/Au:S/C:P/I:P/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:S): A single authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

8.0

6.4

[email protected]

Affected software / configurations for CVE-2020-26255

Vendor	Product	Version	Raw CPE
getkirby	kirby	< 3.4.5	cpe:2.3:a:getkirby:kirby::::::::
getkirby	panel	< 2.5.14	cpe:2.3:a:getkirby:panel::::::::

References for CVE-2020-26255

URL	Tags
https://github.com/getkirby-v2/panel/commit/5a569d4e3ddaea2b6628d7ec1472a3e8bc410881	Patch Third Party Advisory
https://github.com/getkirby/kirby/commit/db8f371b13036861c9cc5ba3e85e27f73fce5e09	Patch Third Party Advisory
https://github.com/getkirby/kirby/releases/tag/3.4.5	Release Notes Third Party Advisory
https://github.com/getkirby/kirby/security/advisories/GHSA-g3h8-cg9x-47qw	Release Notes Third Party Advisory
https://packagist.org/packages/getkirby/cms	Product Third Party Advisory
https://packagist.org/packages/getkirby/panel	Product Third Party Advisory

URL

CVE-2020-26255 | PHP Phar archives could be uploaded and executed in Kirby

Exploit prediction scoring system (EPSS) score for CVE-2020-26255

Common vulnerability scoring system (CVSS) metrics for CVE-2020-26255

Weakness enumeration for CVE-2020-26255

GitHub Security Advisory for CVE-2020-26255

Affected software / configurations for CVE-2020-26255

References for CVE-2020-26255