CVE-2026-98101ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- Not yet scored
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Undergoing Analysis
- Record last updated
- Oct 3, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 882ba1f73c06831f2a21044ebd8864c485ac04f2 before ac51321d3b2391860a935820ebcf4d8b9bb16a8a; from 882ba1f73c06831f2a21044ebd8864c485ac04f2 before dba00514bf668c26cb4900e9f0da84bf96bf065a; 882ba1f73c06831f2a21044ebd8864c485ac04f2 builds before 2c2091e2ee93049fc513ad1e6c99d8b6c809f467; 882ba1f73c06831f2a21044ebd8864c485ac04f2 builds before 20db91a052332ef5552bd2f651ffb9db911cf67b; from 882ba1f73c06831f2a21044ebd8864c485ac04f2 before c073d1b070f171d206b19c98d71739a97f15b3f1; 47c75e3923c8d562fea8daf0ccf31546a7bef0ea; from 5.10.261 before 5.11 | CNA record |
References
- https://git.kernel.org/stable/c/ac51321d3b2391860a935820ebcf4d8b9bb16a8a
- https://git.kernel.org/stable/c/dba00514bf668c26cb4900e9f0da84bf96bf065a
- https://git.kernel.org/stable/c/2c2091e2ee93049fc513ad1e6c99d8b6c809f467
- https://git.kernel.org/stable/c/20db91a052332ef5552bd2f651ffb9db911cf67b
- https://git.kernel.org/stable/c/c073d1b070f171d206b19c98d71739a97f15b3f1
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.