CVE-2025-21956: Linux kernel · drm/amd/display: Assign normalized_pix_clk when color depth = 14
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.4.0-1147.157~18.04.1 : update Linux kernel when convenient.
Data as of 28 Oct 2026, 11:14 UTC
- Patch
- Available – fixed in 5.4.0-1147.157~18.04.1, 5.4.0-1152.159~18.04.1, 5.4.0-1150.159~18.04.1 +87
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7585-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7592-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7597-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7597-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7598-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-3 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
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)
References
- ubuntu.com/security/CVE-2025-21956 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21956 (opens in a new tab)
- git.kernel.org/linus/79e31396fdd7037c503e6add15af7cb00633ea92 (opens in a new tab)
- git.kernel.org/stable/c/04f90b505ad3a6eed474bbaa03167095fef5203a (opens in a new tab)
- git.kernel.org/stable/c/27df30106690969f7d63604f0d49ed8e9bffa2cb (opens in a new tab)
- git.kernel.org/stable/c/79e31396fdd7037c503e6add15af7cb00633ea92 (opens in a new tab)
- git.kernel.org/stable/c/a8f77e1658d78e4a8bb227a83bcee67de97f7634 (opens in a new tab)
- git.kernel.org/stable/c/dc831b38680c47d07e425871a9852109183895cf (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7592-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7597-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7597-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7598-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-3 (opens in a new tab)