# CVE-2026-74338: bpf: Reject sleepable BPF_LSM_CGROUP programs at load time

CVE-2026-74338 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-74338, released August 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-74338
- Priority: High
- CVSS: 7.8 (Low)
- EPSS: 0.0019
- 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-2026-74338

## Description

In the Linux kernel, the following vulnerability has been resolved:  bpf: Reject sleepable BPF_LSM_CGROUP programs at load time  The cgroup shim runs under rcu_read_lock_dont_migrate(), so we should not attach any sleepable BPF programs there. Add support to the verifier to explicitly reject attempts to load sleepable BPF programs destined for LSM cgroup attachment.  Without this, we get the following splat from a BPF_LSM_CGROUP program marked BPF_F_SLEEPABLE attached to file_open when it calls bpf_get_dentry_xattr():    BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1567   in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 34317, name: load   preempt_count: 0, expected: 0   RCU nest depth: 2, expected: 0   Call Trace:    down_read+0x76/0x480    ext4_xattr_get+0x11f/0x700    __vfs_getxattr+0xf0/0x150    bpf_get_dentry_xattr+0xbb/0xf0    bpf_prog_e76a298dac9218c6_test_open+0x6a/0x85    __cgroup_bpf_run_lsm_current+0x326/0x840    bpf_trampoline_6442534646+0x62/0x14d    security_file_open+0x34/0x60    do_dentry_open+0x340/0x1260    vfs_open+0x7a/0x440    path_openat+0x1bac/0x30a0  libbpf provides a .s named section variant for every sleepable program type except lsm_cgroup, reflecting that per-cgroup LSM programs are intended to only run in a non-sleepable context.  The above splat was obtained by bypassing libbpf by using bpf(2) directly.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-74338](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74338.md) | Aug 15, 2026 |
| Linux | linux Debian 14 | 7.1.5-1 | [DEBIAN-CVE-2026-74338](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74338.md) | Aug 15, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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