CVE-2023-53624 [Medium] | Integer Overflow in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_fq: fix integer overflow of "credit" if sch_fq is configured with "initial quantum" having values greater than INT_MAX, the first assignment of "credit" does signed integer overflow to a very negative value. In this situation, the syzkaller script provided by Cristoph triggers the CPU soft-lockup warning even with few sockets. It's not an infinite loop, but "credit" wasn't probably meant to be minus 2Gb for each new flow. Capping "initial quantum" to INT_MAX proved to fix the issue. v2: validation of "initial quantum" is done in fq_policy, instead of open coding in fq_change() _ suggested by Jakub Kicinski

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.02%	0.19%	+0.16%
2	2025-10-08	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.02%

0.19%

+0.16%

2025-10-08

—

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-2023-53624

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2023-53624 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-2023-53624
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2023-53624
`suse`	medium	CVE-2023-53624 severity moderate: SUSE including 321 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 474 product×package rows across 46 product lines (Image SLES12-SP5-Azure-BYOS, Image SLES12-SP5-Azure-HPC-BYOS, … (46 product lines)): Known Affected 231, Fixed 126, Known Not Affected 117.	https://www.suse.com/security/cve/CVE-2023-53624/
`ubuntu`	medium	CVE-2023-53624 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, ignored 162, released 116, not-affected 77, needed 41, needs-triage 1.	https://ubuntu.com/security/CVE-2023-53624

Affected software / configurations for CVE-2023-53624

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 3.12, < 5.10.180	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.111	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 6.1.28	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.2, < 6.2.15	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.3, < 6.3.2	cpe:2.3:o:linux:linux_kernel::::::::

References for CVE-2023-53624

URL	Tags
https://git.kernel.org/stable/c/2322462d6f9ad4874f4e3c63df3b5cc00cb1acbd	Patch
https://git.kernel.org/stable/c/4b8a05e3801661a0438fcd0cdef181030d966a5a	Patch
https://git.kernel.org/stable/c/4fbefeab88c6e79753a25099d455d3d59d2946b4	Patch
https://git.kernel.org/stable/c/7041101ff6c3073fd8f2e99920f535b111c929cb	Patch
https://git.kernel.org/stable/c/85f24cb2f10b2b0f2882e5786a09b4790bb3a0ad	Patch
https://git.kernel.org/stable/c/d0b43125ec892aeb1b03e5df5aab595097da225a	Patch

URL

CVE-2023-53624 | net/sched: sch_fq: fix integer overflow of "credit"

Exploit prediction scoring system (EPSS) score for CVE-2023-53624

Common vulnerability scoring system (CVSS) metrics for CVE-2023-53624

Weakness enumeration for CVE-2023-53624

OS Trackers for CVE-2023-53624

Affected software / configurations for CVE-2023-53624

References for CVE-2023-53624