CVE-2023-53477Public exploit

Kernel warning via undersized nexthop message buffer

Published Oct 1, 2025 · Updated Oct 1, 2025

Incorrect buffer-size calculation in Linux IPv6 routing allows local users to trigger a kernel warning via crafted nexthop routes. rt6_nlmsg_size() multiplies only the parent fib6_info nexthop length by the sibling count, omitting lwtunnel encapsulation lengths present only on siblings. Local access with permission to create IPVLAN interfaces and add IPv6 routes is required; the published trace reaches inet6_rt_notify(), with no reported confidentiality or integrity impact.

CVSS severity5.5
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect buffer-size calculation in Linux IPv6 routing allows local users to trigger a kernel warning via crafted nexthop routes. rt6_nlmsg_size() multiplies only the parent fib6_info nexthop length by the sibling count, omitting lwtunnel encapsulation lengths present only on siblings. Local access with permission to create IPVLAN interfaces and add IPv6 routes is required; the published trace reaches inet6_rt_notify(), with no reported confidentiality or integrity impact.

The record

CVE
CVE-2023-53477
Published
Oct 1, 2025
Updated
Oct 1, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 1, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.11
  2. Affected versionversion=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <4cc59f386991ec9374cb4bc83dbe1c0b5a95033f
  3. Affected versionversion=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <aa75d826c221e8d48607aef33836cf872a159cf1
  4. Affected versionversion=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <aba298b35619213ca787d08d472049627d8cd012
  5. Affected versionversion=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <da26369377f0b671c14692e2d65ceb38131053e1
  6. Affected versionversion=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <dcdddb5f490890d058ea1f194d661219e92fe88d
  7. Affected versionversion=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <e11e4d524eba2d3c8fdf897d7ce3853f7573bae9

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.11; version=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <4cc59f386991ec9374cb4bc83dbe1c0b5a95033f; version=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <aa75d826c221e8d48607aef33836cf872a159cf1; version=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <aba298b35619213ca787d08d472049627d8cd012; version=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <da26369377f0b671c14692e2d65ceb38131053e1; version=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <dcdddb5f490890d058ea1f194d661219e92fe88d; version=beb1afac518dec5a15dc92ba8f0ca016dcf457b4 <e11e4d524eba2d3c8fdf897d7ce3853f7573bae9

Published CVSS scores

5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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