Advisory [CVE-2026-64096] fix use-after-free in orig_node RCU release
This security Red Hat Linux advisory covers CVE-2026-64096.
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Summary
In the Linux kernel, the following vulnerability has been resolved: batman-adv: mcast: fix use-after-free in orig_node RCU release batadv_mcast_purge_orig() removes entries from RCU-protected hlists but does not wait for an RCU grace period before returning. Concurrent RCU readers may still accesses references to those entries at the point of removal.
RCU-protected readers trying to operate on entries like orig->mcast_want_all_ipv6_node will then access already freed memory. Fix this by moving batadv_mcast_purge_orig() to batadv_orig_node_release(), just before the call_rcu() invocation.
This ensures RCU readers that were active at purge time have drained before the orig_node memory is reclaimed. A flaw was found in the `batman-adv` (Better Approach To Mobile Ad-hoc Networking) multicast (mcast) module of the Linux kernel.
The `batadv_mcast_purge_orig()` function removes entries from RCU (Read-Copy-Update)-protected lists without ensuring that all active readers have finished accessing those entries.
This can lead to a use-after-free vulnerability, where concurrent operations may attempt to access memory that has already been released, potentially causing system instability or a denial of service. Red Hat severity: not rated.
Weakness: CWE-825.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
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