CVE-2025-21747: Linux kernel · drm/ast: astdp: Fix timeout for enabling video signal
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 29 Oct 2026, 23:28 UTC
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 27 Feb 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinux-raspi-realtimepkg:deb/ubuntu/linux-raspi-realtime?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-allwinner-5.19pkg:deb/ubuntu/linux-allwinner-5.19?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-aws-5.19pkg:deb/ubuntu/linux-aws-5.19?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-aws-6.2pkg:deb/ubuntu/linux-aws-6.2?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-aws-6.5pkg:deb/ubuntu/linux-aws-6.5?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-azure-5.19pkg:deb/ubuntu/linux-azure-5.19?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available that increases the timeout from 200 milliseconds to 1 second in the ast driver code. Applying the updated Linux kernel versions that include this fix will eliminate the timeout warnings. No additional mitigation is required as the issue is cosmetic and does not affect video signal enabling.
Description
CVE-2025-21747 addresses a timeout issue in the ASTDP transmitter within the Linux kernel's ast driver. The transmitter sometimes takes up to 1 second to enable the video signal, but the timeout was incorrectly set to 200 milliseconds, causing kernel warning messages. This issue is cosmetic and does not prevent the video signal from being enabled. The problem has existed for some time but only recent driver versions produce the warning.
References
- ubuntu.com/security/CVE-2025-21747 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21747 (opens in a new tab)
- git.kernel.org/linus/fd39c41bcd82d5ebaaebadb944eab5598c668a90 (opens in a new tab)
- git.kernel.org/stable/c/589839379031cce220c9cab9f27cb5477195067e (opens in a new tab)
- git.kernel.org/stable/c/fd39c41bcd82d5ebaaebadb944eab5598c668a90 (opens in a new tab)