CVE-2026-98101
In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source() pmc->sflist is read locklessly under rcu_read_lock() by inet6_mc_check() during packet reception in the UDP and RAW multicast receive paths. ip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place when adding or removing a source filter. Additionally, when expanding the filter buffer, newpsl was published via rcu_assign_pointer() before writing the new source into the array. Because 16-byte struct in6_addr writes are not atomic and array shifting is not synchronized with RCU readers, concurrent readers in inet6_mc_check() could read torn IPv6 addresses or observe duplicated/missed source entries. Fix this by switching ip6_mc_source() to copy-on-write RCU updates: allocate and fully populate newpsl before publishing it via rcu_assign_pointer(), and reclaim the old filter via kfree_rcu(), matching ip6_mc_msfilter(). Also remove the now unused IP6_SFBLOCK macro.
Affected versions
Linux kernel versions
5.10.261,
5.13
and later are affected. Fixed in
6.6.158,
6.12.112,
6.18.53,
7.2.7,
7.3-rc2
and their respective stable series.
References
5 totalFrequently asked questions
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What is CVE-2026-98101?
CVE-2026-98101 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 5.10.261 onward and has been patched in 6.6.158, 6.12.112, 6.18.53 and others. CVE-2026-98101 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-98101?
Yes. CVE-2026-98101 has been patched. Fixed versions include 6.6.158, 6.12.112, 6.18.53 and others. If you are running Linux kernel 5.10.261 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-98101 actively exploited?
No. CVE-2026-98101 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.