bpf: Fix bpf_xdp_store_bytes proto for read-only arg
Summary
| CVE | CVE-2026-45886 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-27 14:17:02 UTC |
| Updated | 2026-05-27 14:48:31 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: bpf: Fix bpf_xdp_store_bytes proto for read-only arg While making some maps in Cilium read-only from the BPF side, we noticed that the bpf_xdp_store_bytes proto is incorrect. In particular, the verifier was throwing the following error: ; ret = ctx_store_bytes(ctx, l3_off + offsetof(struct iphdr, saddr), &nat->address, 4, 0); 635: (79) r1 = *(u64 *)(r10 -144) ; R1=ctx() R10=fp0 fp-144=ctx() 636: (b4) w2 = 26 ; R2=26 637: (b4) w4 = 4 ; R4=4 638: (b4) w5 = 0 ; R5=0 639: (85) call bpf_xdp_store_bytes#190 write into map forbidden, value_size=6 off=0 size=4 nat comes from a BPF_F_RDONLY_PROG map, so R3 is a PTR_TO_MAP_VALUE. The verifier checks the helper's memory access to R3 in check_mem_size_reg, as it reaches ARG_CONST_SIZE argument. The third argument has expected type ARG_PTR_TO_UNINIT_MEM, which includes the MEM_WRITE flag. The verifier thus checks for a BPF_WRITE access on R3. Given R3 points to a read-only map, the check fails. Conversely, ARG_PTR_TO_UNINIT_MEM can also lead to the helper reading from uninitialized memory. This patch simply fixes the expected argument type to match that of bpf_skb_store_bytes. |
Risk And Classification
EPSS: 0.000240000 probability, percentile 0.073730000 (date 2026-05-31)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 3f364222d032eea6b245780e845ad213dab28cdd ffb5d1c5e3933b947fc7303ad68bf0c536d0c85e git | Not specified |
| CNA | Linux | Linux | affected 3f364222d032eea6b245780e845ad213dab28cdd ddc34a1b85505c919026ddc82fafdada9a160b15 git | Not specified |
| CNA | Linux | Linux | affected 3f364222d032eea6b245780e845ad213dab28cdd 0db169a91381a473b7974021d1c02f8da72c5775 git | Not specified |
| CNA | Linux | Linux | affected 3f364222d032eea6b245780e845ad213dab28cdd d7b87adeb0eb539b9b824b101bb14fb01e41240b git | Not specified |
| CNA | Linux | Linux | affected 3f364222d032eea6b245780e845ad213dab28cdd 57f7f6a0ad04a65c8a7a067b2f56cbbf2aec9e52 git | Not specified |
| CNA | Linux | Linux | affected 3f364222d032eea6b245780e845ad213dab28cdd 6557f1565d779851c4db9c488c49c05a47a6e72f git | Not specified |
| CNA | Linux | Linux | affected 5.18 | Not specified |
| CNA | Linux | Linux | unaffected 5.18 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.165 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.128 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.75 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.14 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.19.4 6.19.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/57f7f6a0ad04a65c8a7a067b2f56cbbf2aec9e52 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/6557f1565d779851c4db9c488c49c05a47a6e72f | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/ffb5d1c5e3933b947fc7303ad68bf0c536d0c85e | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/0db169a91381a473b7974021d1c02f8da72c5775 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/ddc34a1b85505c919026ddc82fafdada9a160b15 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/d7b87adeb0eb539b9b824b101bb14fb01e41240b | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.