VulnerabilityPublished 18 Jun 2025Updated 5 Nov 2026

CVE-2025-38037: Linux kernel · vxlan: Annotate FDB data races

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f6205f8215f12a96518ac9469ff76294ae7bd612 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 21:04 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in f6205f8215f12a96518ac9469ff76294ae7bd612, e033da39fc6abbddab6c29624acef80757f273fa, a6644aeb8ddf196dec5f8e782293c36f065df4d7 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ d342894c5d2f8c7df194c793ec4059656e09ca31, < f6205f8215f12a96518ac9469ff76294ae7bd612	Fixed in f6205f8215f12a96518ac9469ff76294ae7bd612
LinuxLinux	Affected ≥ d342894c5d2f8c7df194c793ec4059656e09ca31, < e033da39fc6abbddab6c29624acef80757f273fa	Fixed in e033da39fc6abbddab6c29624acef80757f273fa
LinuxLinux	Affected ≥ d342894c5d2f8c7df194c793ec4059656e09ca31, < a6644aeb8ddf196dec5f8e782293c36f065df4d7	Fixed in a6644aeb8ddf196dec5f8e782293c36f065df4d7
LinuxLinux	Affected ≥ d342894c5d2f8c7df194c793ec4059656e09ca31, < 784b78295a3a58bf052339dd669e6e03710220d3	Fixed in 784b78295a3a58bf052339dd669e6e03710220d3
LinuxLinux	Affected ≥ d342894c5d2f8c7df194c793ec4059656e09ca31, < 87d076987a9ba106c83412fcd113656f71af05a1	Fixed in 87d076987a9ba106c83412fcd113656f71af05a1
LinuxLinux	Affected ≥ d342894c5d2f8c7df194c793ec4059656e09ca31, < 13cba3f837903f7184d6e9b6137d5165ffe82a8f	Fixed in 13cba3f837903f7184d6e9b6137d5165ffe82a8f

Description

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 &

References

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