VulnerabilityPublished 25 Sep 2026Updated 21 Oct 2026

CVE-2026-98099: Linux kernel · ipv6: mcast: use rcu_assign_pointer() for __rcu list updates

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in afca229b39acc2590976b3e4f6e0fe76cededc60 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:18 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in afca229b39acc2590976b3e4f6e0fe76cededc60, 49d7e1b456ba2f3ee08b3e264d999c09992cde8e, 2e46b0c9fcf7e10b64ce1630b925f47918d1f7f6 +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 ≥ 456b61bca8ee324ab6c18b065e632c9a8c88aa39, < afca229b39acc2590976b3e4f6e0fe76cededc60	Fixed in afca229b39acc2590976b3e4f6e0fe76cededc60
LinuxLinux	Affected ≥ 456b61bca8ee324ab6c18b065e632c9a8c88aa39, < 49d7e1b456ba2f3ee08b3e264d999c09992cde8e	Fixed in 49d7e1b456ba2f3ee08b3e264d999c09992cde8e
LinuxLinux	Affected ≥ 456b61bca8ee324ab6c18b065e632c9a8c88aa39, < 2e46b0c9fcf7e10b64ce1630b925f47918d1f7f6	Fixed in 2e46b0c9fcf7e10b64ce1630b925f47918d1f7f6
LinuxLinux	Affected ≥ 456b61bca8ee324ab6c18b065e632c9a8c88aa39, < 0e3e3cec28c4d1bf29948da40b4e9e5d44f7852b	Fixed in 0e3e3cec28c4d1bf29948da40b4e9e5d44f7852b
LinuxLinux	Affected ≥ 456b61bca8ee324ab6c18b065e632c9a8c88aa39, < 0c8f56c583c3250408367880c98e4d6fbc929315	Fixed in 0c8f56c583c3250408367880c98e4d6fbc929315
LinuxLinux	Affected =2.6.38	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: use rcu_assign_pointer() for __rcu list updates Several places in net/ipv6/mcast.c update RCU-protected lists (np->ipv6_mc_list, idev->mc_list, idev->mc_tomb) using direct pointer assignments instead of rcu_assign_pointer(): 1. In __ipv6_dev_mc_dec(), unlinking a group from idev->mc_list did: *map = ma->next; without rcu_assign_pointer() while concurrent readers traverse idev->mc_list locklessly under rcu_read_lock(). 2. In ipv6_sock_mc_drop() and __ipv6_sock_mc_close(), unlinking a group from np->ipv6_mc_list directly assigned *lnk = mc_lst->next and np->ipv6_mc_list = mc_lst->next without rcu_assign_pointer(), racing with lockless readers in inet6_mc_check(). 3. In __ipv6_sock_mc_join(), mc_lst->next was initialized to np->ipv6_mc_list via raw assignment before publishing mc_lst. 4. In mld_del_delrec() and __ipv6_dev_mc_inc(), __rcu source pointers passed into rcu_assign_pointer() lacked explicit dereference helpers. Fix these by consistently using rcu_assign_pointer() along with mc_dereference() / sock_dereference().

References

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