# CVE-2026-74337: bpf: Fix NMI/tracepoint re-entry deadlock on lru locks CVE-2026-74337 is fixed in 20 products on 1 platform, first by DEBIAN-CVE-2026-74337, released August 15, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-74337 - Priority: Routine - CVSS: 5.5 (Moderate) - EPSS: 0.0021 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Aug 15, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-74337 ## Description In the Linux kernel, the following vulnerability has been resolved: bpf: Fix NMI/tracepoint re-entry deadlock on lru locks NMI and tracepoint BPF programs can re-enter the per-CPU or global LRU lock that bpf_lru_pop_free()/push_free() already hold on the same CPU, AA-deadlocking. Lockdep reports "inconsistent {INITIAL USE} -> {IN-NMI}" on &l->lock (syzbot c69a0a2c816716f1e0d5) and "possible recursive locking detected" on &loc_l->lock (syzbot 18b26edb69b2e19f3b33). Prior trylock and rqspinlock based fixes (see links) were nacked because compromised on reliability. This patch converts every LRU lock site to rqspinlock_t and adds a recovery path for some failure windows to avoid node leaks. Failure recovery: - *_pop_free top-level: return NULL; prealloc_lru_pop() already treats that as no-free-element (-ENOMEM). - Cross-CPU steal: skip the victim's locked loc_l, try next CPU. - Post-steal local lock fail: publish stolen node to lockless per-CPU free_llist; next pop on this CPU picks it up. - push_free fail: mark node pending_free=1. __local_list_flush(), __local_list_pop_pending() reclaim the node from pending_list. __bpf_lru_list_shrink_inactive() reclaims the node from inactive list. Nodes from active list are reclaimed by __bpf_lru_list_shrink() or after __bpf_lru_list_rotate_active() demotes it to the inactive. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel-livepatch-6.18.41-94.142 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | linux Debian 14 | 7.1.5-1 | [DEBIAN-CVE-2026-74337](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74337.md) | Aug 15, 2026 | | Linux | microvm-kernel6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.41-94.142.amzn2023 | [ALAS2023-2026-2071](https://patchblox.com/security/data/fix/linux/alas2023-2026-2071.md) | Aug 31, 2026 | --- Data as of 2026-11-08T06:59:42Z UTC. 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