VulnerabilityPublished 25 Sep 2026Updated 19 Oct 2026

CVE-2026-98026: Linux kernel · net: bridge: mcast: properly convert mglist to rcu

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f7bf57e94a5d6214b87be08486cb33836fbfa573 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f7bf57e94a5d6214b87be08486cb33836fbfa573, 98247c8264d2076f81fa114bdfa2c2271953ac7c, 38ab2a435001a3c4dbeb70a52f5921e1ccd66f55 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 07f8ac4a1e26e8283542cdaf658a6e2a12fd6980, < f7bf57e94a5d6214b87be08486cb33836fbfa573	Fixed in f7bf57e94a5d6214b87be08486cb33836fbfa573
LinuxLinux	Affected ≥ 07f8ac4a1e26e8283542cdaf658a6e2a12fd6980, < 98247c8264d2076f81fa114bdfa2c2271953ac7c	Fixed in 98247c8264d2076f81fa114bdfa2c2271953ac7c
LinuxLinux	Affected ≥ 07f8ac4a1e26e8283542cdaf658a6e2a12fd6980, < 38ab2a435001a3c4dbeb70a52f5921e1ccd66f55	Fixed in 38ab2a435001a3c4dbeb70a52f5921e1ccd66f55
LinuxLinux	Affected ≥ 07f8ac4a1e26e8283542cdaf658a6e2a12fd6980, < 37cb9a81600da8250f24e25edc07253b62353cbe	Fixed in 37cb9a81600da8250f24e25edc07253b62353cbe
LinuxLinux	Affected ≥ 07f8ac4a1e26e8283542cdaf658a6e2a12fd6980, < 4b772869a1e5f9da5cef5b9c722ec0aa424ee0a0	Fixed in 4b772869a1e5f9da5cef5b9c722ec0aa424ee0a0
LinuxLinux	Affected =3.16	Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel. Users should update to a kernel version that includes the fix identified by the commits f7bf57e94a5d6214b87be08486cb33836fbfa573, 98247c8264d2076f81fa114bdfa2c2271953ac7c, 38ab2a435001a3c4dbeb70a52f5921e1ccd66f55, 37cb9a81600da8250f24e25edc07253b62353cbe, or 4b772869a1e5f9da5cef5b9c722ec0aa424ee0a0. No additional mitigation steps are indicated beyond applying the patch.

Description

A vulnerability in the Linux kernel's network bridge multicast handling was fixed by properly converting the mglist to use RCU (Read-Copy-Update) mechanisms. The flaw involved improper use of RCU helpers when unlisting port groups, leading to premature freeing of data structures without waiting for the RCU grace period. This could cause use-after-free issues in the multicast list handling.

Impact

Improper RCU usage in the multicast bridge code could lead to use-after-free conditions, potentially causing kernel crashes or memory corruption. This impacts the stability and security of the Linux kernel networking stack, particularly in environments using network bridging with multicast traffic.

Summary

The Linux kernel's bridge multicast code had a bug where the mglist was not properly converted to use RCU. Specifically, the function br_multicast_del_port_group removed port groups without using the correct RCU helper to preserve the next pointer and freed the port group immediately without waiting for the RCU grace period. The only RCU walker, br_multicast_list_adjacent(), was buggy because mglist was never properly converted to RCU. The fix involved converting mglist to RCU and adjusting initialization order and pointer handling to ensure safe concurrent access.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 12:53 UTC

Technical details

References

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