CVE-2025-21956 [Medium] | Security Vulnerability in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Assign normalized_pix_clk when color depth = 14 [WHY & HOW] A warning message "WARNING: CPU: 4 PID: 459 at ... /dc_resource.c:3397 calculate_phy_pix_clks+0xef/0x100 [amdgpu]" occurs because the display_color_depth == COLOR_DEPTH_141414 is not handled. This is observed in Radeon RX 6600 XT. It is fixed by assigning pix_clk * (14 * 3) / 24 - same as the rests. Also fixes the indentation in get_norm_pix_clk. (cherry picked from commit 274a87eb389f58eddcbc5659ab0b180b37e92775)

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-21	0.11%	0.02%	-0.08%
2	2026-01-26	0.03%	0.11%	+0.08%
3	2025-11-01	—	0.03%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-21

0.11%

0.02%

-0.08%

2026-01-26

0.03%

0.11%

+0.08%

2025-11-01

—

0.03%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

OS Trackers for CVE-2025-21956

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2025-21956 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6.	https://security-tracker.debian.org/tracker/CVE-2025-21956
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2025-21956
`suse`	medium	—	https://www.suse.com/security/cve/CVE-2025-21956/
`ubuntu`	medium	CVE-2025-21956 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 192, ignored 154, not-affected 39, needed 21.	https://ubuntu.com/security/CVE-2025-21956

Affected software / configurations for CVE-2025-21956

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 4.15, < 5.4.292	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.5, < 5.10.236	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.180	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 6.1.132	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.2, < 6.6.84	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.7, < 6.12.20	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.13, < 6.13.8	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.14	cpe:2.3:o:linux:linux_kernel:6.14:rc1::::::
linux	linux_kernel	6.14	cpe:2.3:o:linux:linux_kernel:6.14:rc2::::::
linux	linux_kernel	6.14	cpe:2.3:o:linux:linux_kernel:6.14:rc3::::::
linux	linux_kernel	6.14	cpe:2.3:o:linux:linux_kernel:6.14:rc4::::::
linux	linux_kernel	6.14	cpe:2.3:o:linux:linux_kernel:6.14:rc5::::::
linux	linux_kernel	6.14	cpe:2.3:o:linux:linux_kernel:6.14:rc6::::::

References for CVE-2025-21956

URL	Tags
https://git.kernel.org/stable/c/0174a2e5770efee9dbd4b58963ed4d939298ff5e	Patch
https://git.kernel.org/stable/c/04f90b505ad3a6eed474bbaa03167095fef5203a	Patch
https://git.kernel.org/stable/c/0c0016712e5dc23ce4a7e673cbebc24a535d8c8a	Patch
https://git.kernel.org/stable/c/27df30106690969f7d63604f0d49ed8e9bffa2cb	Patch
https://git.kernel.org/stable/c/79e31396fdd7037c503e6add15af7cb00633ea92	Patch
https://git.kernel.org/stable/c/a8f77e1658d78e4a8bb227a83bcee67de97f7634	Patch
https://git.kernel.org/stable/c/cca3ab74f90176099b6392e8e894b52b27b3d080	Patch
https://git.kernel.org/stable/c/dc831b38680c47d07e425871a9852109183895cf	Patch
https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

URL

CVE-2025-21956 | drm/amd/display: Assign normalized_pix_clk when color depth = 14

Exploit prediction scoring system (EPSS) score for CVE-2025-21956

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21956

Weakness enumeration for CVE-2025-21956

OS Trackers for CVE-2025-21956

Affected software / configurations for CVE-2025-21956

References for CVE-2025-21956