{"id":"CVE-2026-45886","summary":"bpf: Fix bpf_xdp_store_bytes proto for read-only arg","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix bpf_xdp_store_bytes proto for read-only arg\n\nWhile making some maps in Cilium read-only from the BPF side, we noticed\nthat the bpf_xdp_store_bytes proto is incorrect. In particular, the\nverifier was throwing the following error:\n\n  ; ret = ctx_store_bytes(ctx, l3_off + offsetof(struct iphdr, saddr),\n                          &nat-\u003eaddress, 4, 0);\n  635: (79) r1 = *(u64 *)(r10 -144)     ; R1=ctx() R10=fp0 fp-144=ctx()\n  636: (b4) w2 = 26                     ; R2=26\n  637: (b4) w4 = 4                      ; R4=4\n  638: (b4) w5 = 0                      ; R5=0\n  639: (85) call bpf_xdp_store_bytes#190\n  write into map forbidden, value_size=6 off=0 size=4\n\nnat comes from a BPF_F_RDONLY_PROG map, so R3 is a PTR_TO_MAP_VALUE.\nThe verifier checks the helper's memory access to R3 in\ncheck_mem_size_reg, as it reaches ARG_CONST_SIZE argument. The third\nargument has expected type ARG_PTR_TO_UNINIT_MEM, which includes the\nMEM_WRITE flag. The verifier thus checks for a BPF_WRITE access on R3.\nGiven R3 points to a read-only map, the check fails.\n\nConversely, ARG_PTR_TO_UNINIT_MEM can also lead to the helper reading\nfrom uninitialized memory.\n\nThis patch simply fixes the expected argument type to match that of\nbpf_skb_store_bytes.","modified":"2026-06-27T11:55:05.961066382Z","published":"2026-05-27T12:16:58Z","related":["SUSE-SU-2026:22099-1","SUSE-SU-2026:22108-1","SUSE-SU-2026:22112-1","SUSE-SU-2026:22127-1","SUSE-SU-2026:22137-1","SUSE-SU-2026:2482-1","SUSE-SU-2026:2591-1","SUSE-SU-2026:2630-1","SUSE-SU-2026:2632-1","SUSE-SU-2026:2658-1","openSUSE-SU-2026:20965-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45886.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0db169a91381a473b7974021d1c02f8da72c5775"},{"type":"WEB","url":"https://git.kernel.org/stable/c/57f7f6a0ad04a65c8a7a067b2f56cbbf2aec9e52"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6557f1565d779851c4db9c488c49c05a47a6e72f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d7b87adeb0eb539b9b824b101bb14fb01e41240b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ddc34a1b85505c919026ddc82fafdada9a160b15"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ffb5d1c5e3933b947fc7303ad68bf0c536d0c85e"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45886.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45886"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3f364222d032eea6b245780e845ad213dab28cdd"},{"fixed":"ffb5d1c5e3933b947fc7303ad68bf0c536d0c85e"},{"fixed":"ddc34a1b85505c919026ddc82fafdada9a160b15"},{"fixed":"0db169a91381a473b7974021d1c02f8da72c5775"},{"fixed":"d7b87adeb0eb539b9b824b101bb14fb01e41240b"},{"fixed":"57f7f6a0ad04a65c8a7a067b2f56cbbf2aec9e52"},{"fixed":"6557f1565d779851c4db9c488c49c05a47a6e72f"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-45886.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.18.0"},{"fixed":"6.1.165"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.128"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.75"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.14"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-45886.json"}}],"schema_version":"1.7.5"}