CVE-2026-23204 | net/sched: cls_u32: use skb_header_pointer_careful()

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: use skb_header_pointer_careful() skb_header_pointer() does not fully validate negative @offset values. Use skb_header_pointer_careful() instead. GangMin Kim provided a report and a repro fooling u32_classify(): BUG: KASAN: slab-out-of-bounds in u32_classify+0x1180/0x11b0 net/sched/cls_u32.c:221

Published: 2026-02-14 Last update: 2026-06-01 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-23204 is rated Low Risk (29.2/100): CVSS High severity, with low exploitation likelihood (EPSS 0.12%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-23204

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.12% +0.10%
2 2026-02-15 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23204

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.1 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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:H)
Serious risk that confidential data gets exposed in a big 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 5.2 416baaa9-dc9f-4396-8d5f-8c081fb06d67
7.1 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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:H)
Serious risk that confidential data gets exposed in a big 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 5.2 [email protected]

Weakness enumeration for CVE-2026-23204

GitHub Security Advisory for CVE-2026-23204

GHSA-rf63-9f5h-hhg6 · Severity: high — In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: use...

OS Trackers for CVE-2026-23204

vendor priority summary link
debian not yet assigned CVE-2026-23204 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5, open 1. https://security-tracker.debian.org/tracker/CVE-2026-23204
redhat medium — https://access.redhat.com/security/cve/CVE-2026-23204
suse high — https://www.suse.com/security/cve/CVE-2026-23204/
ubuntu medium CVE-2026-23204 medium priority: Ubuntu including 157 source packages (linux, linux-allwinner-5.19, …), 1256 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): DNE 871, ignored 173, needed 123, released 83, pending 5, not-affected 1. https://ubuntu.com/security/CVE-2026-23204

Affected software / configurations for CVE-2026-23204

Vendor Product Version Raw CPE
linux linux_kernel >= 2.6.35.1, < 6.6.124 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.70 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.18.10 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 2.6.35 cpe:2.3:o:linux:linux_kernel:2.6.35:-:*:*:*:*:*:*
linux linux_kernel 2.6.35 cpe:2.3:o:linux:linux_kernel:2.6.35:rc2:*:*:*:*:*:*
linux linux_kernel 2.6.35 cpe:2.3:o:linux:linux_kernel:2.6.35:rc3:*:*:*:*:*:*
linux linux_kernel 2.6.35 cpe:2.3:o:linux:linux_kernel:2.6.35:rc4:*:*:*:*:*:*
linux linux_kernel 2.6.35 cpe:2.3:o:linux:linux_kernel:2.6.35:rc5:*:*:*:*:*:*
linux linux_kernel 2.6.35 cpe:2.3:o:linux:linux_kernel:2.6.35:rc6:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc1:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc2:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc3:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc4:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc5:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc6:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc7:*:*:*:*:*:*
linux linux_kernel 6.19 cpe:2.3:o:linux:linux_kernel:6.19:rc8:*:*:*:*:*:*

References for CVE-2026-23204

cvelogic Threat Intelligence