{"cve":"CVE-2026-98101","nvd":{"published":"2026-09-25T11:17:39.830","modified":"2026-10-19T10:18:07.260","status":"Undergoing Analysis","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()\n\npmc->sflist is read locklessly under rcu_read_lock() by\ninet6_mc_check() during packet reception in the UDP and RAW\nmulticast receive paths.\n\nip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place\nwhen adding or removing a source filter. Additionally, when expanding\nthe filter buffer, newpsl was published via rcu_assign_pointer()\nbefore writing the new source into the array.\n\nBecause 16-byte struct in6_addr writes are not atomic and array\nshifting is not synchronized with RCU readers, concurrent readers in\ninet6_mc_check() could read torn IPv6 addresses or observe\nduplicated/missed source entries.\n\nFix this by switching ip6_mc_source() to copy-on-write RCU updates:\nallocate and fully populate newpsl before publishing it via\nrcu_assign_pointer(), and reclaim the old filter via kfree_rcu(),\nmatching ip6_mc_msfilter().\n\nAlso remove the now unused IP6_SFBLOCK macro.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/20db91a052332ef5552bd2f651ffb9db911cf67b","https://git.kernel.org/stable/c/2c2091e2ee93049fc513ad1e6c99d8b6c809f467","https://git.kernel.org/stable/c/ac51321d3b2391860a935820ebcf4d8b9bb16a8a","https://git.kernel.org/stable/c/c073d1b070f171d206b19c98d71739a97f15b3f1","https://git.kernel.org/stable/c/dba00514bf668c26cb4900e9f0da84bf96bf065a"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-98101","score":0.00168,"percentile":0.06029,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}