ipv6: mcast: fix RCU list diversion in ip6_mc_del1_src() (CVE-2026-98102) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-98102

ipv6: mcast: fix RCU list diversion in ip6_mc_del1_src()

Answer in brief

CVE-2026-98102 records a Unknown severity vulnerability in ipv6: mcast: fix RCU list diversion in ip6_mc_del1_src(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=4b200e398953c237c86d32bf26d4cb2a96556a6f <4352737297b262e8367675c19a7dc6a9f53c97af \|\| >=4b200e398953c237c86d32bf26d4cb2a96556a6f <8d4fe5c13f5056faa6deb09a90e24a89f9ebfad4 \|\| >=4b200e398953c237c86d32bf26d4cb2a96556a6f <5149c60c406595b56fda0c6e9aae7fd287f636aa \|\| >=4b200e398953c237c86d32bf26d4cb2a96556a6f <93b49239840b91313adbd77b8b52993eff2d08c1 \|\| 86c49119f0353f857cc08030ec9e4ebaab3d5a64 \|\| >=5.10.261 <5.11	4352737297b262e8367675c19a7dc6a9f53c97af, 8d4fe5c13f5056faa6deb09a90e24a89f9ebfad4, 5149c60c406595b56fda0c6e9aae7fd287f636aa, 93b49239840b91313adbd77b8b52993eff2d08c1, 5.11
Linux/Linuxgeneric	5.13	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 4352737297b262e8367675c19a7dc6a9f53c97af if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: fix RCU list diversion in ip6_mc_del1_src() When removing a source filter whose count reaches zero, ip6_mc_del1_src() unlinks psf from pmc->mca_sources. If the filter was previously active, the code moved psf directly into pmc->mca_tomb by updating psf->sf_next. Because pmc->mca_sources is traversed locklessly under RCU (e.g. by ipv6_chk_mcast_addr()), mutating psf->sf_next before a grace period elapses diverts concurrent readers to the tombstone list. Consequently, readers miss remaining active sources in pmc->mca_sources and improperly examine deleted tombstone entries. Fix this by allocating a new tombstone node for pmc->mca_tomb (as done in sf_setstate()) and retiring the original psf via kfree_rcu().

Quoted source text, attributed separately from HOL analysis.