CVE-2025-39851

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-09-22. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

vxlan: Fix NPD when refreshing an FDB entry with a nexthop object

VXLAN FDB entries can point to either a remote destination or an FDB nexthop group. The latter is usually used in EVPN deployments where learning is disabled.

However, when learning is enabled, an incoming packet might try to refresh an FDB entry that points to an FDB nexthop group and therefore does not have a remote. Such packets should be dropped, but they are only dropped after dereferencing the non-existent remote, resulting in a NPD [1] which can be reproduced using [2].

Fix by dropping such packets earlier. Remove the misleading comment from first_remote_rcu().

[1] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] CPU: 13 UID: 0 PID: 361 Comm: mausezahn Not tainted 6.17.0-rc1-virtme-g9f6b606b6b37 #1 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 RIP: 0010:vxlan_snoop+0x98/0x1e0 [...] Call Trace: vxlan_encap_bypass+0x209/0x240 encap_bypass_if_local+0xb1/0x100 vxlan_xmit_one+0x1375/0x17e0 vxlan_xmit+0x6b4/0x15f0 dev_hard_start_xmit+0x5d/0x1c0 __dev_queue_xmit+0x246/0xfd0 packet_sendmsg+0x113a/0x1850 __sock_sendmsg+0x38/0x70 __sys_sendto+0x126/0x180 __x64_sys_sendto+0x24/0x30 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x4b/0x53

[2] #!/bin/bash

ip address add 192.0.2.1/32 dev lo ip address add 192.0.2.2/32 dev lo

ip nexthop add id 1 via 192.0.2.3 fdb ip nexthop add id 10 group 1 fdb

ip link add name vx0 up type vxlan id 10010 local 192.0.2.1 dstport 12345 localbypass ip link add name vx1 up type vxlan id 10020 local 192.0.2.2 dstport 54321 learning

bridge fdb add 00:11:22:33:44:55 dev vx0 self static dst 192.0.2.2 port 54321 vni 10020 bridge fdb add 00:aa:bb:cc:dd:ee dev vx1 self static nhid 10

mausezahn vx0 -a 00:aa:bb:cc:dd:ee -b 00:11:22:33:44:55 -c 1 -q

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
25(Track)
EG Risk 25/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

September 19, 2025

Last Modified

August 5, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
No patch confirmed yet.
generic

vxlan: Fix NPD when refreshing an FDB entry with a nexthop object - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6ead38147ebb813f08be6ea8ef547a0e4c09559a
generic

vxlan: Fix NPD when refreshing an FDB entry with a nexthop object - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4ff4f3104da6507e0f118c63c4560dfdeb59dce3
generic

vxlan: Fix NPD when refreshing an FDB entry with a nexthop object - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/0e8630f24c14d9c655d19eabe2e52a9e9f713307

Vendor Advisories for CVE-2025-39851(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-6.8 (6.8.0-106.106) @ noble2026-05-29ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1049.52.1) @ noble2026-05-29ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1052.55+fips1) @ noble2026-05-29ubuntu
ubuntulinux-tools-aws-edge (6.8.0-1050.53~22.04.1) @ jammy2026-05-29ubuntu
ubuntulinux-tools-realtime-hwe-22.04 (6.8.1-1045.46~22.04.1) @ jammy2026-05-29ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1051.57) @ noble2026-05-29ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1051.57~22.04.1) @ jammy2026-05-29ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2040.41) @ noble2026-05-29ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1052.58+fips1) @ noble2026-05-29ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-05-29ubuntu
linuxKernel @ 6.12.46—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 7.2~rc5-1~exp1 (496 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 7.2~rc7-1~exp1 (350 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1, 6.12.41-1, 6.12.43-1, 6.12.43-1~bpo12+16.12.48-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 6.16~rc7-1~exp1 (64 versions)6.16.6-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(10)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 5× in last 7d / 24× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 141 total refreshes for this CVE.

  1. 2026-09-20 20:15 UTCEPSS rescore
  2. 2026-09-18 19:27 UTCEPSS rescore
  3. 2026-09-17 19:29 UTCEPSS rescore
  4. 2026-09-16 14:07 UTCEPSS rescore
  5. 2026-09-16 05:14 UTCEPSS rescore
  6. 2026-09-13 16:46 UTCEPSS rescore
  7. 2026-09-12 15:00 UTCEPSS rescore
  8. 2026-09-11 14:52 UTCEPSS rescore
  9. 2026-09-11 09:35 UTCEPSS rescore
  10. 2026-09-10 09:33 UTCEPSS rescore
  11. 2026-09-08 21:59 UTCEPSS rescore
  12. 2026-09-07 16:00 UTCEPSS rescore
  13. 2026-09-07 11:18 UTCOSV refresh
  14. 2026-09-06 13:46 UTCEPSS rescore
  15. 2026-09-04 05:05 UTCEPSS rescore
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:38 UTCEPSS rescore
  19. 2026-08-30 19:16 UTCEPSS rescore
  20. 2026-08-30 01:21 UTCEPSS rescore
  21. 2026-08-28 21:40 UTCEPSS rescore
  22. 2026-08-27 14:24 UTCEPSS rescore
  23. 2026-08-26 14:45 UTCEPSS rescore
  24. 2026-08-25 13:48 UTCEPSS rescore
  25. 2026-08-23 00:18 UTCEPSS rescore
Show 75 more
  1. 2026-08-21 23:48 UTCEPSS rescore
  2. 2026-08-20 22:54 UTCEPSS rescore
  3. 2026-08-20 20:31 UTCOSV refresh
  4. 2026-08-19 17:03 UTCEPSS rescore
  5. 2026-08-19 17:03 UTCEPSS rescore
  6. 2026-08-18 13:47 UTCEPSS rescore
  7. 2026-08-17 13:46 UTCEPSS rescore
  8. 2026-08-16 14:55 UTCEPSS rescore
  9. 2026-08-16 02:13 UTCEPSS rescore
  10. 2026-08-15 01:29 UTCEPSS rescore
  11. 2026-08-13 21:59 UTCEPSS rescore
  12. 2026-08-12 13:50 UTCEPSS rescore
  13. 2026-08-09 13:46 UTCEPSS rescore
  14. 2026-08-08 16:36 UTCEPSS rescore
  15. 2026-08-07 16:26 UTCEPSS rescore
  16. 2026-08-06 13:46 UTCEPSS rescore
  17. 2026-08-05 12:57 UTCEG score recompute
  18. 2026-08-05 12:57 UTCVendor advisory
  19. 2026-08-05 12:57 UTCGHSA enrichment
  20. 2026-08-04 15:09 UTCEPSS rescore
  21. 2026-08-04 10:37 UTCEPSS rescore
  22. 2026-08-03 10:35 UTCEPSS rescore
  23. 2026-08-01 04:15 UTCEPSS rescore
  24. 2026-07-30 16:27 UTCEPSS rescore
  25. 2026-07-30 06:51 UTCEG score recompute
  26. 2026-07-30 06:51 UTCGHSA enrichment
  27. 2026-07-30 01:29 UTCEPSS rescore
  28. 2026-07-28 15:35 UTCEPSS rescore
  29. 2026-07-26 14:54 UTCEPSS rescore
  30. 2026-07-23 19:11 UTCOSV refresh
  31. 2026-07-23 02:55 UTCEG score recompute
  32. 2026-07-22 14:07 UTCEPSS rescore
  33. 2026-07-22 14:07 UTCEPSS rescore
  34. 2026-07-21 15:24 UTCEPSS rescore
  35. 2026-07-20 17:07 UTCEPSS rescore
  36. 2026-07-19 14:30 UTCEPSS rescore
  37. 2026-07-19 14:30 UTCEPSS rescore
  38. 2026-07-19 02:28 UTCEPSS rescore
  39. 2026-07-19 02:28 UTCEPSS rescore
  40. 2026-07-18 10:04 UTCEPSS rescore
  41. 2026-07-18 10:04 UTCEPSS rescore
  42. 2026-07-16 17:02 UTCEPSS rescore
  43. 2026-07-15 16:57 UTCEPSS rescore
  44. 2026-07-15 16:57 UTCEPSS rescore
  45. 2026-07-15 01:59 UTCEPSS rescore
  46. 2026-07-15 01:59 UTCEPSS rescore
  47. 2026-07-13 22:29 UTCEPSS rescore
  48. 2026-07-13 22:29 UTCEPSS rescore
  49. 2026-07-13 06:12 UTCEPSS rescore
  50. 2026-07-12 05:46 UTCEPSS rescore
  51. 2026-07-11 08:27 UTCEPSS rescore
  52. 2026-07-11 08:27 UTCEPSS rescore
  53. 2026-07-09 19:09 UTCEPSS rescore
  54. 2026-07-09 19:09 UTCEPSS rescore
  55. 2026-07-07 13:45 UTCEPSS rescore
  56. 2026-07-06 16:27 UTCEPSS rescore
  57. 2026-07-06 16:27 UTCEPSS rescore
  58. 2026-07-06 13:41 UTCOSV refresh
  59. 2026-07-06 02:23 UTCEPSS rescore
  60. 2026-07-05 02:30 UTCEPSS rescore
  61. 2026-07-04 06:30 UTCEPSS rescore
  62. 2026-07-01 15:06 UTCEPSS rescore
  63. 2026-07-01 15:06 UTCEPSS rescore
  64. 2026-06-30 23:22 UTCEPSS rescore
  65. 2026-06-30 23:22 UTCEPSS rescore
  66. 2026-06-29 14:06 UTCEPSS rescore
  67. 2026-06-29 14:06 UTCEPSS rescore
  68. 2026-06-28 14:07 UTCEPSS rescore
  69. 2026-06-28 14:07 UTCEPSS rescore
  70. 2026-06-27 03:08 UTCEPSS rescore
  71. 2026-06-27 03:08 UTCEPSS rescore
  72. 2026-06-25 13:49 UTCEPSS rescore
  73. 2026-06-25 13:49 UTCEPSS rescore
  74. 2026-06-24 14:04 UTCEPSS rescore
  75. 2026-06-24 14:04 UTCEPSS rescore

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2025-39851?
CVE-2025-39851 is a medium vulnerability published on September 19, 2025. In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix NPD when refreshing an FDB entry with a nexthop object VXLAN FDB entries can point to either a remote destination or an FDB nexthop group. The latter is usually used in EVPN deployments where learning is disabled.…
When was CVE-2025-39851 disclosed?
CVE-2025-39851 was first published in the National Vulnerability Database on September 19, 2025, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-39851 actively exploited?
CVE-2025-39851 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 77.9% of all scored CVEs.
What is the CVSS score of CVE-2025-39851?
CVE-2025-39851 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-39851?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-39851, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-39851

Explore →

Is Your Infrastructure Affected by CVE-2025-39851?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs