High · CVSS 7.8CVE-2026-43091

xfrm: Wait for RCU readers during policy netns exitCVE-2026-43091

Answer in brief

CVE-2026-43091 records a High severity (CVSS 7.8) vulnerability in xfrm: Wait for RCU readers during policy netns exit. 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 May 6, 2026Updated Oct 16, 2026Source checked Oct 16, 2026First seen by HOL Oct 16, 2026Material review Oct 16, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.8
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.8. 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	>=e1e551bc56302b80ff930c966f9985095fb1b70d <b66920a3348c0f63ba18365248fa21fbf0b3a937 \|\| >=e1e551bc56302b80ff930c966f9985095fb1b70d <438b1f668ad58f46ce699bb48e4698a7839e3f9e \|\| >=e1e551bc56302b80ff930c966f9985095fb1b70d <3733fce2871c9bca9dd18a1a23b1432ea215a094 \|\| >=e1e551bc56302b80ff930c966f9985095fb1b70d <33a3149dd81a1e2f52b80ee1e0fc380b39f3d028 \|\| >=e1e551bc56302b80ff930c966f9985095fb1b70d <069daad4f2ae9c5c108131995529d5f02392c446	b66920a3348c0f63ba18365248fa21fbf0b3a937, 438b1f668ad58f46ce699bb48e4698a7839e3f9e, 3733fce2871c9bca9dd18a1a23b1432ea215a094, 33a3149dd81a1e2f52b80ee1e0fc380b39f3d028, 069daad4f2ae9c5c108131995529d5f02392c446
Linux/Linuxgeneric	4.9	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to b66920a3348c0f63ba18365248fa21fbf0b3a937 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
May 6, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 16, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: xfrm: Wait for RCU readers during policy netns exit xfrm_policy_fini() frees the policy_bydst hash tables after flushing the policy work items and deleting all policies, but it does not wait for concurrent RCU readers to leave their read-side critical sections first. The policy_bydst tables are published via rcu_assign_pointer() and are looked up through rcu_dereference_check(), so netns teardown must also wait for an RCU grace period before freeing the table memory. Fix this by adding synchronize_rcu() before freeing the policy hash tables.

Quoted source text, attributed separately from HOL analysis.