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NVD / CVE Program· CNA Linux

CVE-2026-74657: ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Fixed version: Linux Linux 0f0ca602941d0a81ae9514943ca06c55159c6385, 4a5dfbae5179f6574695012a980476254df2d295, 4ff9548d84945d2cbf9e4c207288063a200ea397; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0f0ca602941d0a81ae9514943ca06c55159c6385, 4a5dfbae5179f6574695012a980476254df2d295, 4ff9548d84945d2cbf9e4c207288063a200ea397; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Aug 22, 2026
Updated
Oct 14, 2026
EPSS
0.1% · 7th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.2affected
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before 57195f0ab5cfbb5ee0864e5aff15ceb48f5a5e28affected · git
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before 0f0ca602941d0a81ae9514943ca06c55159c6385affected · git
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before 5307a53599fa762c06e475ee4a375252074fd324affected · git
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before 7f80ad373ce4a7af5367ff273cea0f16e91387f3affected · git
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before 4a5dfbae5179f6574695012a980476254df2d295affected · git
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before a59edda6eda1252340354322d8ab318b2e9052fbaffected · git
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before 9b22f13524fa0de0d963bbd3002df6c28bae3395affected · git
    • d15662682db232da77136cd348f4c9df312ca6f9 and later · before 4ff9548d84945d2cbf9e4c207288063a200ea397affected · git
    • before 5.2not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.105-16.12.105-1
Debian:14linuxbefore 7.1.9-17.1.9-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-74655Aug 22, 2026 · serial: qcom-geni: fix TX DMA buffer flush
    35Monitor
  • ← EarlierCVE-2026-74656Aug 22, 2026 · ipv4: fix use-after-free in fib_nhc_update_mtu()
    31Monitor
  • Later →CVE-2026-74658Aug 22, 2026 · futex: Prevent robust futex exit race some more
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0f0ca602941d0a81ae9514943ca06c55159c6385Vendor (CNA)
Linux Linux4a5dfbae5179f6574695012a980476254df2d295Vendor (CNA)
Linux Linux4ff9548d84945d2cbf9e4c207288063a200ea397Vendor (CNA)
Linux Linux5307a53599fa762c06e475ee4a375252074fd324Vendor (CNA)
Linux Linux57195f0ab5cfbb5ee0864e5aff15ceb48f5a5e28Vendor (CNA)
Linux Linux7f80ad373ce4a7af5367ff273cea0f16e91387f3Vendor (CNA)
Linux Linux9b22f13524fa0de0d963bbd3002df6c28bae3395Vendor (CNA)
Linux Linuxa59edda6eda1252340354322d8ab318b2e9052fbVendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.06.6.152.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.107-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records