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CVE-2026-74657

ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops

CVSS score

4.4

EPSS probability

%0.2

Risk score

0.0

Published

1 mo ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Official patch verified

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Vulnerability description

DayBreach CVE AI Research

CVE-2026-74657 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

In the Linux kernel, the following vulnerability has been resolved: ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops fib_nlmsg_size() still estimates nexthop space as if every gateway is encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an IPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA. As a result, route notifications can allocate an skb that is too small. fib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the WARN_ON() that marks such failures as a fib_nlmsg_size() bug. With panic_on_warn set, this becomes a kernel panic. Mirror the actual nexthop dump layout in fib_nlmsg_size(): account for IPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop layout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is actually present.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-74657 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1linuxLinux View
2linuxLinux View
Total affected vendors: 1|Products: 2

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
4.4CVSS 3.x—CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:HMicrosoft MSRC

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

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reference

Yama veya çözüm referansı

Open source
Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-74657 is associated with the following CWEs:

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')CWE-20: Improper Input Validation

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-74657 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureYerel erişim
PermissionsHigh
UserGerekmiyor

Official Sources and Advisories

https://git.kernel.org/stable/c/57195f0ab5cfbb5ee0864e5aff15ceb48f5a5e28vendor-advisoryhttps://git.kernel.org/stable/c/0f0ca602941d0a81ae9514943ca06c55159c6385vendor-advisoryhttps://git.kernel.org/stable/c/5307a53599fa762c06e475ee4a375252074fd324vendor-advisoryhttps://git.kernel.org/stable/c/7f80ad373ce4a7af5367ff273cea0f16e91387f3vendor-advisoryhttps://git.kernel.org/stable/c/4a5dfbae5179f6574695012a980476254df2d295vendor-advisoryhttps://git.kernel.org/stable/c/a59edda6eda1252340354322d8ab318b2e9052fbvendor-advisoryhttps://git.kernel.org/stable/c/9b22f13524fa0de0d963bbd3002df6c28bae3395vendor-advisoryhttps://git.kernel.org/stable/c/4ff9548d84945d2cbf9e4c207288063a200ea397vendor-advisoryhttps://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgradepatch

CVSS Vector Radar Chart

4.4 / 10
Attack VectorLocalComplexityLowPrivilegesHighUser Interact.NoneConfidentialityLowIntegrityNoneAvailabilityHigh

Vulnerability Scoring Details

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Attack VectorLocal
Attack ComplexityLow
Privileges RequiredHigh privileges
User InteractionNone required
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)High

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