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Linux Kernel EUVDEUVD-2026-38903

| CVE-2026-53035 MEDIUM
Improper Locking (CWE-667)
2026-06-24 Linux GHSA-9ppp-c797-fg56
Information Disclosure Linux Red Hat Suse
5.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.5 MEDIUM

Local access with CAP_BPF required (PR:L); no confidentiality or integrity impact; recursive spinlock deadlock yields high availability loss.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.5 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Analysis Generated
Jul 15, 2026 - 14:54 vuln.today
CVSS changed
Jul 15, 2026 - 14:52 NVD
5.5 (MEDIUM)
Patch available
Jun 24, 2026 - 18:02 EUVD
CVE Published
Jun 24, 2026 - 16:29 nvd
MEDIUM 5.5
CVE Published
Jun 24, 2026 - 16:29 cve.org
UNKNOWN (no severity yet)

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

bpf, sockmap: Fix af_unix iter deadlock

bpf_iter_unix_seq_show() may deadlock when lock_sock_fast() takes the fast path and the iter prog attempts to update a sockmap. Which ends up spinning at sock_map_update_elem()'s bh_lock_sock():

WARNING: possible recursive locking detected test_progs/1393 is trying to acquire lock: ffff88811ec25f58 (slock-AF_UNIX){+...}-{3:3}, at: sock_map_update_elem+0xdb/0x1f0

but task is already holding lock: ffff88811ec25f58 (slock-AF_UNIX){+...}-{3:3}, at: __lock_sock_fast+0x37/0xe0

other info that might help us debug this: Possible unsafe locking scenario:

CPU0 ---- lock(slock-AF_UNIX); lock(slock-AF_UNIX);

* DEADLOCK *

May be due to missing lock nesting notation

4 locks held by test_progs/1393: #0: ffff88814b59c790 (&p->lock){+.+.}-{4:4}, at: bpf_seq_read+0x59/0x10d0 #1: ffff88811ec25fd8 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: bpf_seq_read+0x42c/0x10d0 #2: ffff88811ec25f58 (slock-AF_UNIX){+...}-{3:3}, at: __lock_sock_fast+0x37/0xe0 #3: ffffffff85a6a7c0 (rcu_read_lock){....}-{1:3}, at: bpf_iter_run_prog+0x51d/0xb00

Call Trace: dump_stack_lvl+0x5d/0x80 print_deadlock_bug.cold+0xc0/0xce __lock_acquire+0x130f/0x2590 lock_acquire+0x14e/0x2b0 _raw_spin_lock+0x30/0x40 sock_map_update_elem+0xdb/0x1f0 bpf_prog_2d0075e5d9b721cd_dump_unix+0x55/0x4f4 bpf_iter_run_prog+0x5b9/0xb00 bpf_iter_unix_seq_show+0x1f7/0x2e0 bpf_seq_read+0x42c/0x10d0 vfs_read+0x171/0xb20 ksys_read+0xff/0x200 do_syscall_64+0x6b/0x3a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e

AnalysisAI

The Linux kernel's BPF sockmap subsystem deadlocks when a BPF iterator program iterating over AF_UNIX sockets via bpf_iter_unix_seq_show() simultaneously attempts to update a sockmap entry during the same execution context. When lock_sock_fast() takes the spinlock fast path and holds slock-AF_UNIX, any subsequent sock_map_update_elem() call within the BPF iterator program spins indefinitely attempting to re-acquire the same spinlock on the same CPU, causing an unrecoverable kernel deadlock and loss of system availability. This is not confirmed actively exploited (not in CISA KEV), no public exploit has been identified, and EPSS at 0.17% (7th percentile) confirms negligible current exploitation interest; the real-world risk is constrained to specialized BPF workloads with specific capability requirements.

Technical ContextAI

The vulnerability resides at the intersection of two Linux kernel subsystems: the BPF iterator framework (bpf_iter) and the sockmap implementation for AF_UNIX sockets. CWE-667 (Improper Locking) precisely identifies the root cause - a recursive spinlock acquisition. bpf_iter_unix_seq_show() acquires slock-AF_UNIX via lock_sock_fast() when it takes the fast (spinlock) path rather than sleeping. The attached BPF iterator program then executes within this locked context. If the BPF program calls bpf_map_update_elem() on a sockmap, this invokes sock_map_update_elem(), which calls bh_lock_sock() and attempts to re-acquire the same slock-AF_UNIX spinlock already held by the calling thread - a classic recursive spinlock deadlock. The kernel's lock validator (lockdep) detects and reports this as a WARNING: possible recursive locking detected. Affected CPE is cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*, covering the kernel from the introducing commit (2c860a43dd77) through the patched stable releases across branches 6.1, 6.6, 6.12, 6.18, 7.0, and 7.1.

RemediationAI

The definitive fix is to upgrade to a patched kernel release: 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10, or 7.1 depending on the active stable branch. Patch commits are available at https://git.kernel.org/stable/ and can be cherry-picked onto custom kernels. Where an immediate kernel upgrade is not operationally feasible, the following compensating controls can reduce exposure: first, set kernel.unprivileged_bpf_disabled=2 (or =1 for less restrictive blocking) via sysctl to prevent non-privileged users from loading BPF programs - note this will break unprivileged eBPF tools and monitoring agents that run without CAP_SYS_ADMIN. Second, deploy a BPF LSM or seccomp policy that prohibits bpf_map_update_elem() calls within iterator-context BPF programs - this requires custom policy authoring and will break any legitimate sockmap-update logic in existing BPF programs. Neither workaround eliminates the root cause; patching remains the required resolution.

Same weakness CWE-667 – Improper Locking

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.177 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.155 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.206 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.152 Affected
Image SLES15-SP7-Azure-3P Image SLES15-SP7-Azure-Basic Image SLES15-SP7-Azure-Standard Image SLES15-SP7-HPC-Azure Affected
Image SLES15-SP7-BYOS-Azure Image SLES15-SP7-BYOS-GCE Image SLES15-SP7-CHOST-BYOS-Aliyun Image SLES15-SP7-CHOST-BYOS-Azure Image SLES15-SP7-CHOST-BYOS-EC2 Image SLES15-SP7-CHOST-BYOS-GCE Image SLES15-SP7-CHOST-BYOS-GDC Image SLES15-SP7-CHOST-BYOS-SAP-CCloud Image SLES15-SP7-EC2 Image SLES15-SP7-EC2-ECS-HVM Image SLES15-SP7-GCE Image SLES15-SP7-HPC-BYOS-Azure Image SLES15-SP7-HPC-BYOS-EC2 Image SLES15-SP7-HPC-BYOS-GCE Image SLES15-SP7-Hardened-BYOS-Azure Image SLES15-SP7-Hardened-BYOS-EC2 Image SLES15-SP7-Hardened-BYOS-GCE Image SLES15-SP7-SAPCAL-Azure Image SLES15-SP7-SAPCAL-EC2 Image SLES15-SP7-SAPCAL-GCE Affected
Image SLES15-SP7-SAP-Azure Image SLES15-SP7-SAP-Azure-3P Image SLES15-SP7-SAP-BYOS-Azure Image SLES15-SP7-SAP-BYOS-EC2 Image SLES15-SP7-SAP-BYOS-GCE Image SLES15-SP7-SAP-EC2 Image SLES15-SP7-SAP-GCE Image SLES15-SP7-SAP-Hardened-Azure Image SLES15-SP7-SAP-Hardened-BYOS-Azure Image SLES15-SP7-SAP-Hardened-BYOS-EC2 Image SLES15-SP7-SAP-Hardened-BYOS-GCE Image SLES15-SP7-SAP-Hardened-GCE Affected

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EUVD-2026-38903 vulnerability details – vuln.today
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