CVE-2025-21747 [Medium] | Security Vulnerability in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: drm/ast: astdp: Fix timeout for enabling video signal The ASTDP transmitter sometimes takes up to 1 second for enabling the video signal, while the timeout is only 200 msec. This results in a kernel error message. Increase the timeout to 1 second. An example of the error message is shown below. [ 697.084433] ------------[ cut here ]------------ [ 697.091115] ast 0000:02:00.0: [drm] drm_WARN_ON(!__ast_dp_wait_enable(ast, enabled)) [ 697.091233] WARNING: CPU: 1 PID: 160 at drivers/gpu/drm/ast/ast_dp.c:232 ast_dp_set_enable+0x123/0x140 [ast] [...] [ 697.272469] RIP: 0010:ast_dp_set_enable+0x123/0x140 [ast] [...] [ 697.415283] Call Trace: [ 697.420727] <TASK> [ 697.425908] ? show_trace_log_lvl+0x196/0x2c0 [ 697.433304] ? show_trace_log_lvl+0x196/0x2c0 [ 697.440693] ? drm_atomic_helper_commit_modeset_enables+0x30a/0x470 [ 697.450115] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.458059] ? __warn.cold+0xaf/0xca [ 697.464713] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.472633] ? report_bug+0x134/0x1d0 [ 697.479544] ? handle_bug+0x58/0x90 [ 697.486127] ? exc_invalid_op+0x13/0x40 [ 697.492975] ? asm_exc_invalid_op+0x16/0x20 [ 697.500224] ? preempt_count_sub+0x14/0xc0 [ 697.507473] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.515377] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.523227] drm_atomic_helper_commit_modeset_enables+0x30a/0x470 [ 697.532388] drm_atomic_helper_commit_tail+0x58/0x90 [ 697.540400] ast_mode_config_helper_atomic_commit_tail+0x30/0x40 [ast] [ 697.550009] commit_tail+0xfe/0x1d0 [ 697.556547] drm_atomic_helper_commit+0x198/0x1c0 This is a cosmetical problem. Enabling the video signal still works even with the error message. The problem has always been present, but only recent versions of the ast driver warn about missing the timeout.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-07	0.04%	0.10%	+0.06%
2	2025-02-27	—	0.04%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-07

0.04%

0.10%

+0.06%

2025-02-27

—

0.04%

—

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-2025-21747

vendor	priority	summary	link
`debian`	unimportant	CVE-2025-21747 unimportant priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2025-21747
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2025-21747
`suse`	medium	CVE-2025-21747 severity moderate: SUSE including 26 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 198 product×package rows across 40 product lines (SLES-LTSS-TERADATA 15 SP2, SUSE Linux Enterprise High Availability Extension 12 SP5, … (40 product lines)): Known Not Affected 198.	https://www.suse.com/security/cve/CVE-2025-21747/
`ubuntu`	medium	CVE-2025-21747 medium priority: Ubuntu including 128 source packages (linux, linux-allwinner-5.19, …), 1024 status rows across 8 suites (bionic, focal, jammy, noble, oracular, trusty, upstream, xenial): DNE 702, ignored 146, not-affected 115, released 61.	https://ubuntu.com/security/CVE-2025-21747

Affected software / configurations for CVE-2025-21747

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 6.13, < 6.13.3	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.14	cpe:2.3:o:linux:linux_kernel:6.14:rc1::::::

References for CVE-2025-21747

URL	Tags
https://git.kernel.org/stable/c/589839379031cce220c9cab9f27cb5477195067e	Patch
https://git.kernel.org/stable/c/fd39c41bcd82d5ebaaebadb944eab5598c668a90	Patch

URL

CVE-2025-21747 | drm/ast: astdp: Fix timeout for enabling video signal

Exploit prediction scoring system (EPSS) score for CVE-2025-21747

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21747

Weakness enumeration for CVE-2025-21747

OS Trackers for CVE-2025-21747

Affected software / configurations for CVE-2025-21747

References for CVE-2025-21747