CVE-2025-38124 | net: fix udp gso skb_segment after pull from frag_list

In the Linux kernel, the following vulnerability has been resolved: net: fix udp gso skb_segment after pull from frag_list Commit a1e40ac5b5e9 ("net: gso: fix udp gso fraglist segmentation after pull from frag_list") detected invalid geometry in frag_list skbs and redirects them from skb_segment_list to more robust skb_segment. But some packets with modified geometry can also hit bugs in that code. We don't know how many such cases exist. Addressing each one by one also requires touching the complex skb_segment code, which risks introducing bugs for other types of skbs. Instead, linearize all these packets that fail the basic invariants on gso fraglist skbs. That is more robust. If only part of the fraglist payload is pulled into head_skb, it will always cause exception when splitting skbs by skb_segment. For detailed call stack information, see below. Valid SKB_GSO_FRAGLIST skbs - consist of two or more segments - the head_skb holds the protocol headers plus first gso_size - one or more frag_list skbs hold exactly one segment - all but the last must be gso_size Optional datapath hooks such as NAT and BPF (bpf_skb_pull_data) can modify fraglist skbs, breaking these invariants. In extreme cases they pull one part of data into skb linear. For UDP, this causes three payloads with lengths of (11,11,10) bytes were pulled tail to become (12,10,10) bytes. The skbs no longer meets the above SKB_GSO_FRAGLIST conditions because payload was pulled into head_skb, it needs to be linearized before pass to regular skb_segment. skb_segment+0xcd0/0xd14 __udp_gso_segment+0x334/0x5f4 udp4_ufo_fragment+0x118/0x15c inet_gso_segment+0x164/0x338 skb_mac_gso_segment+0xc4/0x13c __skb_gso_segment+0xc4/0x124 validate_xmit_skb+0x9c/0x2c0 validate_xmit_skb_list+0x4c/0x80 sch_direct_xmit+0x70/0x404 __dev_queue_xmit+0x64c/0xe5c neigh_resolve_output+0x178/0x1c4 ip_finish_output2+0x37c/0x47c __ip_finish_output+0x194/0x240 ip_finish_output+0x20/0xf4 ip_output+0x100/0x1a0 NF_HOOK+0xc4/0x16c ip_forward+0x314/0x32c ip_rcv+0x90/0x118 __netif_receive_skb+0x74/0x124 process_backlog+0xe8/0x1a4 __napi_poll+0x5c/0x1f8 net_rx_action+0x154/0x314 handle_softirqs+0x154/0x4b8 [118.376811] [C201134] rxq0_pus: [name:bug&]kernel BUG at net/core/skbuff.c:4278! [118.376829] [C201134] rxq0_pus: [name:traps&]Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP [118.470774] [C201134] rxq0_pus: [name:mrdump&]Kernel Offset: 0x178cc00000 from 0xffffffc008000000 [118.470810] [C201134] rxq0_pus: [name:mrdump&]PHYS_OFFSET: 0x40000000 [118.470827] [C201134] rxq0_pus: [name:mrdump&]pstate: 60400005 (nZCv daif +PAN -UAO) [118.470848] [C201134] rxq0_pus: [name:mrdump&]pc : [0xffffffd79598aefc] skb_segment+0xcd0/0xd14 [118.470900] [C201134] rxq0_pus: [name:mrdump&]lr : [0xffffffd79598a5e8] skb_segment+0x3bc/0xd14 [118.470928] [C201134] rxq0_pus: [name:mrdump&]sp : ffffffc008013770

Published: 2025-07-03 Last update: 2026-05-12 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-2025-38124 is rated Low Risk (31.7/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.10%). 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-2025-38124

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 2026-04-29 0.02% 0.10% +0.08%
2 2025-12-18 0.06% 0.02% -0.04%
3 2025-12-11 — 0.06% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-38124

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-2025-38124

GitHub Security Advisory for CVE-2025-38124

GHSA-gvvf-v7jc-239r · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: net: fix udp gso skb_segment...

OS Trackers for CVE-2025-38124

vendor priority summary link
debian unimportant CVE-2025-38124 unimportant priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2025-38124
redhat medium — https://access.redhat.com/security/cve/CVE-2025-38124
suse medium CVE-2025-38124 severity moderate: SUSE including 519 source package names (2.1.3-6.67:kernel-default-base-6.4.0-32.1.21.10, 2.1.3-7.44:kernel-default-6.4.0-32.1, …), 1151 product×package rows across 217 product lines (Container suse/sl-micro/6.0/base-os-container, Container suse/sl-micro/6.0/kvm-os-container, … (217 product lines)): Fixed 670, Known Affected 231, Known Not Affected 229, First Fixed 21. https://www.suse.com/security/cve/CVE-2025-38124/
ubuntu medium CVE-2025-38124 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, ignored 164, released 137, not-affected 100, needed 2, needs-triage 2, pending 1. https://ubuntu.com/security/CVE-2025-38124

Affected software / configurations for CVE-2025-38124

Vendor Product Version Raw CPE
linux linux_kernel >= 6.1.113, < 6.1.142 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.6.55, < 6.6.94 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.10.14, < 6.11 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.11.3, < 6.12 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.12.1, < 6.12.34 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.15.3 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:-:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc2:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc3:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc4:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc5:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc6:*:*:*:*:*:*
linux linux_kernel 6.12 cpe:2.3:o:linux:linux_kernel:6.12:rc7:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-38124

cvelogic Threat Intelligence