CVE-2026-23254 | net: gro: fix outer network offset

In the Linux kernel, the following vulnerability has been resolved: net: gro: fix outer network offset The udp GRO complete stage assumes that all the packets inserted the RX have the `encapsulation` flag zeroed. Such assumption is not true, as a few H/W NICs can set such flag when H/W offloading the checksum for an UDP encapsulated traffic, the tun driver can inject GSO packets with UDP encapsulation and the problematic layout can also be created via a veth based setup. Due to the above, in the problematic scenarios, udp4_gro_complete() uses the wrong network offset (inner instead of outer) to compute the outer UDP header pseudo checksum, leading to csum validation errors later on in packet processing. Address the issue always clearing the encapsulation flag at GRO completion time. Such flag will be set again as needed for encapsulated packets by udp_gro_complete().

Published: 2026-03-18 Last update: 2026-06-01 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-23254 is rated Low Risk (23.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.02%). 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-2026-23254

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 2026-03-19 — 0.02% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23254

CVSS metrics for this CVE.

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]

Weakness enumeration for CVE-2026-23254

GitHub Security Advisory for CVE-2026-23254

GHSA-wjrj-hvqv-fw2v · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: net: gro: fix outer network...

OS Trackers for CVE-2026-23254

vendor priority summary link
debian unimportant CVE-2026-23254 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-2026-23254
redhat low — https://access.redhat.com/security/cve/CVE-2026-23254
suse medium CVE-2026-23254 severity moderate: SUSE including 25 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 214 product×package rows across 38 product lines (SUSE Linux Enterprise High Availability Extension 15 SP7, SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, … (38 product lines)): Known Not Affected 214. https://www.suse.com/security/cve/CVE-2026-23254/
ubuntu medium CVE-2026-23254 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 169, released 83, not-affected 79, needed 49, pending 5. https://ubuntu.com/security/CVE-2026-23254

Affected software / configurations for CVE-2026-23254

Vendor Product Version Raw CPE
linux linux_kernel >= 6.6.31, < 6.6.124 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.8.10, < 6.9 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.9.1, < 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 6.9 cpe:2.3:o:linux:linux_kernel:6.9:-:*:*:*:*:*:*
linux linux_kernel 6.9 cpe:2.3:o:linux:linux_kernel:6.9:rc7:*:*:*:*:*:*
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-2026-23254

cvelogic Threat Intelligence