CVE-2026-98101

CVE CVE-2026-98101EUVD EUVD-2026-86932Published 2026-09-25T10:35:52.000Z

What the advisory describes

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.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

Linux — Linux 5.13; 882ba1f73c06831f2a21044ebd8864c485ac04f2 <2c2091e2ee93049fc513ad1e6c99d8b6c809f467; 882ba1f73c06831f2a21044ebd8864c485ac04f2 <c073d1b070f171d206b19c98d71739a97f15b3f1; patch: 7.2.7; 882ba1f73c06831f2a21044ebd8864c485ac04f2 <20db91a052332ef5552bd2f651ffb9db911cf67b; patch: 7.3-rc2; patch: 0; 47c75e3923c8d562fea8daf0ccf31546a7bef0ea; 5.10.261 <5.11; patch: 6.18.53

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

Linux — Linux

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