Critical

CVE-2026-74581 — net: ipv6: clear suppressed fib6 rule result

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: clear suppressed fib6 rule result fib6_rule_suppress() drops a suppressed route with ip6_rt_put_flags(), but leaves res->rt6 pointing at the released rt6_info. If no later rule supplies a replacement, fib6_rule_lookup() still sees res.rt6 and returns that stale dst to its caller. A suppressing rule can therefore leak a released route back to rt6_lookup(), and the next put hits rcuref_put_slowpath() from dst_release(). Clear res->rt6 when suppressing the route so suppressed lookups fall through to the null dst instead of reusing the released one.

Published Aug 21, 2026 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.4% (30-day exploitation probability)+5
Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.42%

ahead of 35% of scored CVEs · Oct 15, 2026

Affects

Linux

CVSS base

9.8

Critical · 3 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ 209d35ee34e25f9668c404350a1c86d914c54ffa and < 90c57310e266eb94e4a80d6b15a9ca131d2e82cb≥ 8ef8a76a340ebdb2c2eea3f6fb0ebbed09a16383 and < 5d29b286c9de0b309e94b9ed083aa1a2f429434f≥ cdef485217d30382f3bf6448c54b4401648fe3f1 and < 354db6243eca59e9d187ffbf8b7955b044ce84dc≥ cdef485217d30382f3bf6448c54b4401648fe3f1 and < 6d98c70fe0ba8c7708bfd5b2a5174d2086775daa≥ cdef485217d30382f3bf6448c54b4401648fe3f1 and < 9bad152c42b37499162367fe47867411e62fffa3≥ cdef485217d30382f3bf6448c54b4401648fe3f1 and < dc3ab04220667f254f4348572b2a0b3febff89fb≥ cdef485217d30382f3bf6448c54b4401648fe3f1 and < a341c091ca0bfae377747b1b59a3bd8ebe18a937≥ cdef485217d30382f3bf6448c54b4401648fe3f1 and < 6aea62e433fe1b586202a5fee8b5807ce635e1d7 and 5 more version ee38eb8cf9a7323884c2b8e0adbbeb2192d31e29≥ 5.10.84 and < 5.10.265≥ 5.15.7 and < 5.15.216≥ 5.4.164 and < 5.5version 5.16	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.8	CVSS 3.1	Critical	3.9	5.9	416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
9.8	CVSS 3.1	Critical	—	—	GitHub, Inc. via GitHub Security Advisories
9.8	CVSS 3.1	Critical	—	—	Linux via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)

EPSS over time FIRST

Oct 14, 2026 → Oct 15, 2026 · 2 reading(s) · max 0.42%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · linux/linux
Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 14, 2026
CVSS changed · 9.8
Oct 14, 2026 · NIST National Vulnerability Database
Source status changed · → Received
Oct 14, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 14, 2026 · Alertas do Telegram
CVE published
Aug 21, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 14, 2026 – Oct 14, 2026
1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

10 on the record

git.kernel.org/stable/c/6aea62e433fe1b586202a5fee8b5807ce635e1d7
NIST National Vulnerability Database
git.kernel.org/stable/c/354db6243eca59e9d187ffbf8b7955b044ce84dc
NIST National Vulnerability Database
git.kernel.org/stable/c/6d98c70fe0ba8c7708bfd5b2a5174d2086775daa
NIST National Vulnerability Database
git.kernel.org/stable/c/5d29b286c9de0b309e94b9ed083aa1a2f429434f
NIST National Vulnerability Database
git.kernel.org/stable/c/90c57310e266eb94e4a80d6b15a9ca131d2e82cb
NIST National Vulnerability Database
git.kernel.org/stable/c/dc3ab04220667f254f4348572b2a0b3febff89fb
NIST National Vulnerability Database
github.com/advisories/GHSA-7ph7-58w3-w755
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2026-74581
GitHub Security Advisories
git.kernel.org/stable/c/a341c091ca0bfae377747b1b59a3bd8ebe18a937
NIST National Vulnerability Database
git.kernel.org/stable/c/9bad152c42b37499162367fe47867411e62fffa3
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 17h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 17h
Unknown CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 1d
Unknown CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
Unknown CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-74581 is "net: ipv6: clear suppressed fib6 rule result", rated Critical. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.42% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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