CVE-2025-39850

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 in {arp,neigh}_reduce() when using nexthop objects

When the "proxy" option is enabled on a VXLAN device, the device will suppress ARP requests and IPv6 Neighbor Solicitation messages if it is able to reply on behalf of the remote host. That is, if a matching and valid neighbor entry is configured on the VXLAN device whose MAC address is not behind the "any" remote (0.0.0.0 / ::).

The code currently assumes that the FDB entry for the neighbor's MAC address points to a valid remote destination, but this is incorrect if the entry is associated with an FDB nexthop group. This can result in a NPD [1][3] which can be reproduced using [2][4].

Fix by checking that the remote destination exists before dereferencing it.

[1] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] CPU: 4 UID: 0 PID: 365 Comm: arping Not tainted 6.17.0-rc2-virtme-g2a89cb21162c #2 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 RIP: 0010:vxlan_xmit+0xb58/0x15f0 [...] Call Trace: 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 nexthop add id 1 via 192.0.2.2 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 4789 proxy

ip neigh add 192.0.2.3 lladdr 00:11:22:33:44:55 nud perm dev vx0

bridge fdb add 00:11:22:33:44:55 dev vx0 self static nhid 10

arping -b -c 1 -s 192.0.2.1 -I vx0 192.0.2.3

[3] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] CPU: 13 UID: 0 PID: 372 Comm: ndisc6 Not tainted 6.17.0-rc2-virtmne-g6ee90cb26014 #3 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1v996), BIOS 1.17.0-4.fc41 04/01/2x014 RIP: 0010:vxlan_xmit+0x803/0x1600 [...] Call Trace: dev_hard_start_xmit+0x5d/0x1c0 __dev_queue_xmit+0x246/0xfd0 ip6_finish_output2+0x210/0x6c0 ip6_finish_output+0x1af/0x2b0 ip6_mr_output+0x92/0x3e0 ip6_send_skb+0x30/0x90 rawv6_sendmsg+0xe6e/0x12e0 __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 RIP: 0033:0x7f383422ec77

[4] #!/bin/bash

ip address add 2001:db8:1::1/128 dev lo

ip nexthop add id 1 via 2001:db8:1::1 fdb ip nexthop add id 10 group 1 fdb

ip link add name vx0 up type vxlan id 10010 local 2001:db8:1::1 dstport 4789 proxy

ip neigh add 2001:db8:1::3 lladdr 00:11:22:33:44:55 nud perm dev vx0

bridge fdb add 00:11:22:33:44:55 dev vx0 self static nhid 10

ndisc6 -r 1 -s 2001:db8:1::1 -w 1 2001:db8:1::3 vx0

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
3%
KEV
Not listed

Published

September 19, 2025

Last Modified

January 14, 2026

References (3)

Vendor Advisories for CVE-2025-39850(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-raspi-realtime-6.8 (6.8.0-2040.41) @ noble2026-05-29ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1052.55+fips1) @ noble2026-05-29ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1052.58+fips1) @ noble2026-05-29ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1049.52.1) @ noble2026-05-29ubuntu
ubuntulinux-tools-aws-edge (6.8.0-1050.53~22.04.1) @ jammy2026-05-29ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-05-29ubuntu
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
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.

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 7× in last 7d / 40× 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.

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

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

Frequently asked(5)

What is CVE-2025-39850?
CVE-2025-39850 is a medium vulnerability published on September 19, 2025. In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix NPD in {arp,neigh}_reduce() when using nexthop objects When the "proxy" option is enabled on a VXLAN device, the device will suppress ARP requests and IPv6 Neighbor Solicitation messages if it is able to reply on behalf…
When was CVE-2025-39850 disclosed?
CVE-2025-39850 was first published in the National Vulnerability Database on September 19, 2025, with the most recent update on January 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-39850 actively exploited?
CVE-2025-39850 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 96.6% of all scored CVEs.
What is the CVSS score of CVE-2025-39850?
CVE-2025-39850 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-39850?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-39850, 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.

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