CVE-2025-38037 | vxlan: Annotate FDB data races

In the Linux kernel, the following vulnerability has been resolved: vxlan: Annotate FDB data races The 'used' and 'updated' fields in the FDB entry structure can be accessed concurrently by multiple threads, leading to reports such as [1]. Can be reproduced using [2]. Suppress these reports by annotating these accesses using READ_ONCE() / WRITE_ONCE(). [1] BUG: KCSAN: data-race in vxlan_xmit / vxlan_xmit write to 0xffff942604d263a8 of 8 bytes by task 286 on cpu 0: vxlan_xmit+0xb29/0x2380 dev_hard_start_xmit+0x84/0x2f0 __dev_queue_xmit+0x45a/0x1650 packet_xmit+0x100/0x150 packet_sendmsg+0x2114/0x2ac0 __sys_sendto+0x318/0x330 __x64_sys_sendto+0x76/0x90 x64_sys_call+0x14e8/0x1c00 do_syscall_64+0x9e/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff942604d263a8 of 8 bytes by task 287 on cpu 2: vxlan_xmit+0xadf/0x2380 dev_hard_start_xmit+0x84/0x2f0 __dev_queue_xmit+0x45a/0x1650 packet_xmit+0x100/0x150 packet_sendmsg+0x2114/0x2ac0 __sys_sendto+0x318/0x330 __x64_sys_sendto+0x76/0x90 x64_sys_call+0x14e8/0x1c00 do_syscall_64+0x9e/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x00000000fffbac6e -> 0x00000000fffbac6f Reported by Kernel Concurrency Sanitizer on: CPU: 2 UID: 0 PID: 287 Comm: mausezahn Not tainted 6.13.0-rc7-01544-gb4b270f11a02 #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 [2] #!/bin/bash set +H echo whitelist > /sys/kernel/debug/kcsan echo !vxlan_xmit > /sys/kernel/debug/kcsan ip link add name vx0 up type vxlan id 10010 dstport 4789 local 192.0.2.1 bridge fdb add 00:11:22:33:44:55 dev vx0 self static dst 198.51.100.1 taskset -c 0 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q & taskset -c 2 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q &

Published: 2025-06-18 Last update: 2025-12-18 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-2025-38037 is rated Low Risk (32.8/100): CVSS Medium 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-2025-38037

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 2026-04-14 0.03% 0.12% +0.09%
2 2025-12-19 0.05% 0.03% -0.02%
3 2025-10-17 — 0.05% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-38037

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-2025-38037

OS Trackers for CVE-2025-38037

vendor priority summary link
debian not yet assigned CVE-2025-38037 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 6. https://security-tracker.debian.org/tracker/CVE-2025-38037
redhat low — https://access.redhat.com/security/cve/CVE-2025-38037
suse medium CVE-2025-38037 severity moderate: SUSE including 22 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 86 product×package rows across 20 product lines (SUSE Linux Enterprise High Availability Extension 15 SP7, SUSE Linux Enterprise Live Patching 15 SP6, … (20 product lines)): Will Not Fix 80, Known Not Affected 6. https://www.suse.com/security/cve/CVE-2025-38037/
ubuntu medium CVE-2025-38037 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 169, ignored 168, needed 45, not-affected 21, needs-triage 2, pending 1. https://ubuntu.com/security/CVE-2025-38037

Affected software / configurations for CVE-2025-38037

Vendor Product Version Raw CPE
linux linux_kernel >= 3.7, < 5.4.294 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.5, < 5.10.238 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.185 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.141 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.93 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.31 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.14.9 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-38037

URL Tags
https://git.kernel.org/stable/c/02a33b1035a307453a1da6ce0a1bf3676be287d7 Patch
https://git.kernel.org/stable/c/13cba3f837903f7184d6e9b6137d5165ffe82a8f Patch
https://git.kernel.org/stable/c/4eceb7eae6ea7c950384c34e6dbbe872c981935f Patch
https://git.kernel.org/stable/c/784b78295a3a58bf052339dd669e6e03710220d3 Patch
https://git.kernel.org/stable/c/87d076987a9ba106c83412fcd113656f71af05a1 Patch
https://git.kernel.org/stable/c/a6644aeb8ddf196dec5f8e782293c36f065df4d7 Patch
https://git.kernel.org/stable/c/e033da39fc6abbddab6c29624acef80757f273fa Patch
https://git.kernel.org/stable/c/f6205f8215f12a96518ac9469ff76294ae7bd612 Patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Third Party Advisory
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