CVE-2026-90269
Vulnérabilité non évaluée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject load-acquire from pointers requiring fault protection A BPF_LOAD_ACQ is not rewritten to a BPF_PROBE_MEM load by the verifier, unlike a regular BPF_LDX, so the JIT emits a plain load with no exception table entry and a fault panics the kernel instead of being handled. Reject the source pointer types that a BPF_LDX would have had that fault protection applied to, i.e. the ones bpf_convert_ctx_accesses() turns into BPF_PROBE_MEM: a bare PTR_TO_BTF_ID, PTR_TO_BTF_ID | PTR_UNTRUSTED, PTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED and PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED. This is reachable e.g. by loading ->mm out of a trusted task_struct yields an untrusted pointer to mm_struct, and it is NULL for a kernel thread: [...] SEC("tp_btf/sched_switch") int BPF_PROG(demo, bool preempt, struct task_struct *prev, struct task_struct *next) { struct mm_struct *mm = next->mm; /* untrusted */ out_ldx = (__u64)mm->pgd; /* BPF_LDX */ out_acq = load_acquire(&mm->pgd); /* BPF_LOAD_ACQ */ return 0; } [...] Both dereference the same pointer, but only the BPF_LDX is protected (x86-64 JIT, jump targets shown prog-relative): [...] ; out_ldx = (__u64)mm->pgd; 17: movq $-10485760, %r10 1e: movq %rsi, %r11 21: addq $184, %r11 28: subq %r10, %r11 2b: movabsq $140737498841088, %r10 35: cmpq %r10, %r11 38: ja 0x3e <-- kernel addr? 3a: xorl %edi, %edi <-- no: dst = 0, skip the load 3c: jmp 0x45 3e: movq 184(%rsi), %rdi <-- yes: load + extable entry [...] ; load_acquire(&mm->pgd) 53: movq %rsi, %rdi 56: movq 184(%rdi), %rax <-- no check, no extable entry [...] Note that BPF_PROBE_MEM is not visible in a bpftool xlated dump, as bpf_insn_prepare_dump() rewrites it back to BPF_MEM. A PTR_TRUSTED pointer is deliberately not on the list. Such a load is not converted either, but it does not need to be, since the pointer is guaranteed live, so load-acquire from it stays allowed. The check is gated on BPF_LOAD_ACQ so that atomic RMW and store-release error messages are unchanged; writes (RMW / store-release) to such pointers are already rejected elsewhere, so only load-acquire needs this.
Gravité et risque d'exploitation
CVE-2026-90269 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.21 %, ce qui la place devant 10.1 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 6.18.52, 7.2.6, <5f8ade6e9b7931fc9697394f1b2c4ae833f5ac18, <=*, <=7.2.*, <6.15, <=6.18.*, 0, <7db0a00445f1a40bacfe9b747405c11cb5f10fc9, <c4c8de3bf48d3756ab0f910fe5cc4937d70efdcd, 6.15, 880442305a3908589bf4d6fc1d79edb577ee497c, 7.3) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.