CVE-2021-47109

neighbour: allow NUD_NOARP entries to be forced GCed

MEDIUM
5.5
CVSS Score
Published: March 15, 2024 at 08:14 PM UTC
Updated: August 5, 2026 at 09:24 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: neighbour: allow NUD_NOARP entries to be forced GCed IFF_POINTOPOINT interfaces use NUD_NOARP entries for IPv6. It's possible to fill up the neighbour table with enough entries that it will overflow for valid connections after that. This behaviour is more prevalent after commit 58956317c8de ("neighbor: Improve garbage collection") is applied, as it prevents removal from entries that are not NUD_FAILED, unless they are more than 5s old.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.0 ≤ v < 5.10.435.0 ≤ v < 5.12.105.0 ≤ v < 5.135.0 ≤ v < 5.4.1255.11 ≤ v < 5.12.105.5 ≤ v < 5.10.435.13 rc15.13 rc25.13 rc35.13 rc45.13 rc55.13 rc658956317c8de52009d1a38a721474c24aef74fe7
Vendor states this is fixed in 7a6b1ab7475fd6478eeaf5c9d1163e7a18125c8f (fixed)
Vendor states this is fixed in d17d47da59f726dc4c87caebda3a50333d7e2fd3 (fixed)
Vendor states this is fixed in d99029e6aab62aef0a0251588b2867e77e83b137 (fixed)
Vendor states this is fixed in ddf088d7aaaaacfc836104f2e632b29b1d383cfc (fixed)
Vendor states this is fixed in 5.0 (unaffected)
Vendor states this is fixed in 5.10.43 (unaffected)
Vendor states this is fixed in 5.12.10 (unaffected)
Vendor states this is fixed in 5.13 (unaffected)
Vendor states this is fixed in 5.4.125 (unaffected)

References (4)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/7a6b1ab7475fd6478eeaf5c9d1163e7a18125c8f
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/d17d47da59f726dc4c87caebda3a50333d7e2fd3
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/d99029e6aab62aef0a0251588b2867e77e83b137
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/ddf088d7aaaaacfc836104f2e632b29b1d383cfc

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-190

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