EUVD-2026-64402
GHSA-8qqv-vcf6-q7hx
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Race condition requires precisely timed concurrent map writes (AC:H); PR:L reflects required BPF capability; full kernel compromise impact if race is won.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
4DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix netns reference imbalance in conntrack kfuncs
The opts argument of the BPF conntrack kfuncs can point to a shared map value. __bpf_nf_ct_lookup() and __bpf_nf_ct_alloc_entry() read opts->netns_id separately when acquiring and releasing the network namespace reference.
The reference imbalance can occur as follows:
CPU 0 CPU 1 read opts->netns_id (-1) skip get_net_ns_by_id() write opts->netns_id (id) read opts->netns_id (id) put_net(net) /* no matching get */
The reverse transition leaks the reference. Repeating the unmatched put can destroy a live namespace and crash later users.
The kernel reported:
Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef] RIP: 0010:bpf_prog_test_run_xdp+0x52c/0x1700 Call Trace: __sys_bpf+0x1662/0x50c0 __x64_sys_bpf+0x73/0xb0 do_syscall_64+0xf9/0x540 entry_SYSCALL_64_after_hwframe+0x77/0x7f Kernel panic - not syncing: Fatal exception
Snapshot every input field of opts with READ_ONCE() before validating or using it. The netns_id snapshot keeps the namespace get/put pair balanced, while the other snapshots keep the remaining options from changing partway through an invocation. The individual reads can still observe an inconsistent combination during a concurrent update, but each selected field value remains stable for that invocation.
AnalysisAI
Reference imbalance in the Linux kernel's BPF conntrack kfuncs allows a local attacker with BPF privileges to trigger an unmatched put_net() call that can destroy a live network namespace and cause kernel panic. The flaw affects __bpf_nf_ct_lookup() and __bpf_nf_ct_alloc_entry(), where opts->netns_id is read non-atomically from a shared BPF map value during both namespace acquisition and release. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must have the ability to load and execute BPF programs using conntrack kfuncs - this requires CAP_NET_ADMIN or CAP_SYS_ADMIN (or equivalent capability granted via a permissive seccomp/BPF policy). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) rates this as High severity with local access and low attack complexity. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A local attacker with CAP_NET_ADMIN loads two concurrent BPF programs: the first invokes a conntrack kfunc with opts pointing to a shared BPF map value where netns_id is initially -1, causing the kfunc to skip get_net_ns_by_id(); the second program simultaneously writes a valid netns_id into that map value. The first program then reads the updated netns_id during its put_net() phase and calls put_net() on a namespace it never held a reference to, decrementing the live namespace's reference count to zero. … |
| Remediation | The primary fix is to upgrade to Linux kernel 7.1.9 or 7.2, which contain the READ_ONCE() patches. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, conduct an inventory of Linux systems running BPF workloads (Kubernetes nodes, serverless platforms, container runtimes) and document their specific kernel versions; cross-reference your distribution's security advisory for the exact affected kernel version ranges provided by Red Hat, Canonical, SUSE, or your Linux vendor. …
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External POC / Exploit Code
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