Critical

CVE-2026-74480 — net: bridge: stop fast-leave after deleting a port group

In the Linux kernel, the following vulnerability has been resolved: net: bridge: stop fast-leave after deleting a port group br_multicast_leave_group() iterates mp->ports with pp = &p->next in its fast-leave path. After br_multicast_del_pg() removes p, continuing the loop advances pp through the deleted entry. If multicast-to-unicast was enabled, the bridge can hold multiple port groups for the same port and group with different source MAC addresses. Once multicast-to-unicast is disabled, br_port_group_equal() matches those entries by port only. A fast leave can then delete one entry and continue from its stale next pointer, leaving mp->ports pointing at a deleted port group. Fast leave only needs to remove one matching port group. Break after br_multicast_del_pg() so the loop stops before dereferencing the removed entry.

Published Aug 15, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · 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

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

—

No EPSS score.

Affects

Linux

CVSS base

9.8

Critical · 2 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	≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < d6c32e2e25a9a06ba021030e26b6d602a277eb72≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < 482bcb85139addb4e8ac8ed10baeda3e0aad4031≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < 1a109cc9890d017c41d77e6c82da739579c49f0b≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < 159ad90cb929c033308bb39a2c5f8fbf393b77aa≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < 4695430e8132420bf8de94da3eb36a6cf35fde6b≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < 0309ebbc570000ea0df11c06b69798e5860c5f6f≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < 4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4≥ 6db6f0eae6052b70885562e1733896647ec1d807 and < a39789f211b8a4125f0c70e05b30cf715f4f187d and 1 more version 4.11	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	—	—	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)

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 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 9.8
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Aug 15, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

git.kernel.org/stable/c/d6c32e2e25a9a06ba021030e26b6d602a277eb72
NIST National Vulnerability Database
git.kernel.org/stable/c/159ad90cb929c033308bb39a2c5f8fbf393b77aa
NIST National Vulnerability Database
git.kernel.org/stable/c/482bcb85139addb4e8ac8ed10baeda3e0aad4031
NIST National Vulnerability Database
git.kernel.org/stable/c/4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4
NIST National Vulnerability Database
git.kernel.org/stable/c/a39789f211b8a4125f0c70e05b30cf715f4f187d
NIST National Vulnerability Database
git.kernel.org/stable/c/0309ebbc570000ea0df11c06b69798e5860c5f6f
NIST National Vulnerability Database
git.kernel.org/stable/c/4695430e8132420bf8de94da3eb36a6cf35fde6b
NIST National Vulnerability Database
git.kernel.org/stable/c/1a109cc9890d017c41d77e6c82da739579c49f0b
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 11h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 11h
Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
Unknown CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
Unknown CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d
Unknown CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 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 FIRST EPSS score.
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-2026-74480 is "net: bridge: stop fast-leave after deleting a port group", 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. 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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