bpf: Reject sleepable BPF_LSM_CGROUP programs at load time
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.114, 6.18.57, 7.1.5, 7.2
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Not affected: 3 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2026-74338
- 2026-10-03 Alias added: GHSA-rqq6-3pqg-qxx2
- 2026-10-16 Fix available: Linux/[email protected], Linux/Linux@b4059a1f57eff3e206d44697f64ad81076512760 · CNA
- 2026-10-16 1 new reference · CNA
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-21 Fix available: Linux/Linux@4b9d8bdeb19e709f9bc3c317d48b0c0add3b2b1d, Linux/[email protected], Linux/[email protected] +1 · CNA
- 2026-10-21 2 new references · CNA
- 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@b0c76212af693734e5a2c9e9a48568f99f5bc46c · CNA
- 2026-10-30 1 new reference · CNA
References
Other 6
- https://git.kernel.org/stable/c/b0c76212af693734e5a2c9e9a48568f99f5bc46c
- https://git.kernel.org/stable/c/f0a49d16804d319774388a32d8cdcef319a9e481
- https://git.kernel.org/stable/c/4b9d8bdeb19e709f9bc3c317d48b0c0add3b2b1d
- https://git.kernel.org/stable/c/b4059a1f57eff3e206d44697f64ad81076512760
- https://git.kernel.org/stable/c/be9eaf2bb5db4ad3de61ef739fd268fd7f135737
- https://git.kernel.org/stable/c/5b038319be442c620f774e6fc9e9283deeca1c75
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Sources
- CVE-2026-74338 · CVE Program
- CVE-2026-74338 · NVD
- FIRST EPSS
- GHSA-rqq6-3pqg-qxx2 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-74338 · Red Hat security data · CC BY 4.0
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