CVE-2022-49978 [Medium] | Security Vulnerability in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: fbdev: fb_pm2fb: Avoid potential divide by zero error In `do_fb_ioctl()` of fbmem.c, if cmd is FBIOPUT_VSCREENINFO, var will be copied from user, then go through `fb_set_var()` and `info->fbops->fb_check_var()` which could may be `pm2fb_check_var()`. Along the path, `var->pixclock` won't be modified. This function checks whether reciprocal of `var->pixclock` is too high. If `var->pixclock` is zero, there will be a divide by zero error. So, it is necessary to check whether denominator is zero to avoid crash. As this bug is found by Syzkaller, logs are listed below. divide error in pm2fb_check_var Call Trace: <TASK> fb_set_var+0x367/0xeb0 drivers/video/fbdev/core/fbmem.c:1015 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-14	0.02%	0.05%	+0.03%
2	2025-06-18	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-14

0.02%

0.05%

+0.03%

2025-06-18

—

0.02%

—

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-2022-49978

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2022-49978 not yet assigned 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-2022-49978
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2022-49978
`suse`	medium	—	https://www.suse.com/security/cve/CVE-2022-49978/
`ubuntu`	medium	CVE-2022-49978 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 151, ignored 150, not-affected 99, needed 5, needs-triage 1.	https://ubuntu.com/security/CVE-2022-49978

Affected software / configurations for CVE-2022-49978

Vendor	Product	Version	Raw CPE
linux	linux_kernel	< 4.9.327	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.10, < 4.14.292	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.15, < 4.19.257	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.20, < 5.4.212	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.5, < 5.10.141	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.65	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 5.19.7	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.0	cpe:2.3:o:linux:linux_kernel:6.0:rc1::::::
linux	linux_kernel	6.0	cpe:2.3:o:linux:linux_kernel:6.0:rc2::::::

References for CVE-2022-49978

URL	Tags
https://git.kernel.org/stable/c/0f1174f4972ea9fad6becf8881d71adca8e9ca91	Patch
https://git.kernel.org/stable/c/19f953e7435644b81332dd632ba1b2d80b1e37af	Patch
https://git.kernel.org/stable/c/34c3dea1189525cd533071ed5c176fc4ea8d982b	Patch
https://git.kernel.org/stable/c/3ec326a6a0d4667585ca595f438c7293e5ced7c4	Patch
https://git.kernel.org/stable/c/7d9591b32a9092fc6391a316b56e8016c6181c3d	Patch
https://git.kernel.org/stable/c/7f88cdfea8d7f4dbaf423d808241403b2bb945e4	Patch
https://git.kernel.org/stable/c/8fc778ee2fb2853f7a3531fa7273349640d8e4e9	Patch
https://git.kernel.org/stable/c/cb4bb011a683532841344ca7f281b5e04389b4f8	Patch

URL

CVE-2022-49978 | fbdev: fb_pm2fb: Avoid potential divide by zero error

Exploit prediction scoring system (EPSS) score for CVE-2022-49978

Common vulnerability scoring system (CVSS) metrics for CVE-2022-49978

Weakness enumeration for CVE-2022-49978

OS Trackers for CVE-2022-49978

Affected software / configurations for CVE-2022-49978

References for CVE-2022-49978