CVE-2026-74657

Kernel panic via undersized route notification

Published Aug 22, 2026 · Updated Aug 22, 2026

Denial of service in the Linux IPv4 routing subsystem allows local users to panic the kernel through a route with an IPv6 gateway. fib_nlmsg_size undercounts RTA_VIA nexthop data, causing route notifications to allocate an undersized skb before fib_dump_info returns -EMSGSIZE. A reachable panic requires panic_on_warn to be enabled; otherwise the path produces a kernel warning and failed notification.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in the Linux IPv4 routing subsystem allows local users to panic the kernel through a route with an IPv6 gateway. fib_nlmsg_size undercounts RTA_VIA nexthop data, causing route notifications to allocate an undersized skb before fib_dump_info returns -EMSGSIZE. A reachable panic requires panic_on_warn to be enabled; otherwise the path produces a kernel warning and failed notification.

The record

CVE
CVE-2026-74657
Published
Aug 22, 2026
Updated
Aug 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 22, 2026Record 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=5.2
  2. Affected versionversion=d15662682db232da77136cd348f4c9df312ca6f9 <0f0ca602941d0a81ae9514943ca06c55159c6385
  3. Affected versionversion=d15662682db232da77136cd348f4c9df312ca6f9 <4a5dfbae5179f6574695012a980476254df2d295
  4. Affected versionversion=d15662682db232da77136cd348f4c9df312ca6f9 <4ff9548d84945d2cbf9e4c207288063a200ea397
  5. Affected versionversion=d15662682db232da77136cd348f4c9df312ca6f9 <5307a53599fa762c06e475ee4a375252074fd324
  6. Affected versionversion=d15662682db232da77136cd348f4c9df312ca6f9 <7f80ad373ce4a7af5367ff273cea0f16e91387f3
  7. Affected versionversion=d15662682db232da77136cd348f4c9df312ca6f9 <9b22f13524fa0de0d963bbd3002df6c28bae3395
  8. Affected versionversion=d15662682db232da77136cd348f4c9df312ca6f9 <a59edda6eda1252340354322d8ab318b2e9052fb

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.2; version=d15662682db232da77136cd348f4c9df312ca6f9 <0f0ca602941d0a81ae9514943ca06c55159c6385; version=d15662682db232da77136cd348f4c9df312ca6f9 <4a5dfbae5179f6574695012a980476254df2d295; version=d15662682db232da77136cd348f4c9df312ca6f9 <4ff9548d84945d2cbf9e4c207288063a200ea397; version=d15662682db232da77136cd348f4c9df312ca6f9 <5307a53599fa762c06e475ee4a375252074fd324; version=d15662682db232da77136cd348f4c9df312ca6f9 <7f80ad373ce4a7af5367ff273cea0f16e91387f3; version=d15662682db232da77136cd348f4c9df312ca6f9 <9b22f13524fa0de0d963bbd3002df6c28bae3395; version=d15662682db232da77136cd348f4c9df312ca6f9 <a59edda6eda1252340354322d8ab318b2e9052fb

Published CVSS scores

5.5Red HatCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo