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CVE-2026-80668: Linux

Severity

9.8 (CRITICAL)

Vendor

LINUX

Affected versions

bffcaad9afdfe45d7fc777397d3b83c1e3ebffe5 through before 7ec786f4230c2a9b2eaf97a2d45368933b49d2b2; bffcaad9afdfe45d7fc777

Patch status

Patched

Published

2026-08-28T08:16:52.080

Modified

2026-08-29T07:16:49.200

Why it matters

Critical vulnerability requiring immediate validation against your environment.

Recommended admin actions

• Prioritize validation immediately due to critical CVSS severity.
• Compare installed versions against the affected version range in the advisory.

Technical summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_expect: use conntrack GC to reap expectations This patch replaces the timer API by GC worker approach for expectations, as it already happened in many other subsystems. Use the existing conntrack GC worker to iterate over the local list of expectations in the master conntrack to reap expired expectations. Check IPS_HELPER_BIT to run GC for expectations, set it on for nft_ct expectation which nevers sets it. Hold the expectation spinlock while iterating over the master conntrack expectation list to synchronize with nf_ct_remove_expectations(). This also performs runtime packet path garbage collection through the expectation insertion and lookup functions while walking over one of the chains of the global expectation hashtables. Unconfirmed conntrack entries are skipped since ct->ext can be reallocated and dying are skipped since those will be gone soon. Set on IPS_HELPER_BIT if the helper ct extension is added, then the new GC worker does not need to bump the ct refcount to check if the ct->ext helper is available. This removes the extra bump on the refcount for expectation timers, this allows to remove several nf_ct_expect_put() calls after the unlink, after this update only refcount remains at 1 while on the expectation hashes. This patch implicitly addresses a race with the existing timer API allowing an expectation to access a stale exp->master pointer which has been already released when expectation removal loses races with an expiring timer, ie. timer_del() reporting false. Add a new NF_CT_EXPECT_DEAD flag to reap this expectation via GC. This is needed by nf_conntrack_unexpect_related() which is called in error paths to invalidate newly created expectations that has been added into the hashes. These expectactions cannot be inmediately released as GC or nf_ct_remove_expectations() could race to make it. On expectation insert, the runtime GC reaps stale expectations before checking the expectation limit set by policy. Set current timestamp in nf_ct_expect_alloc(), then add the expectation policy timeout (or custom timeout specified added on top of this) to specify the expectation lifetime.

View the official NVD record for CVE-2026-80668

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.