{"id":"CVE-2026-45933","revision":"26295ad1ca6c427e85390b1f9e3cb1d2","records":[{"revision":"26295ad1ca6c427e85390b1f9e3cb1d2","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-45933","aliases":[],"title":"bpf: Preserve id of register in sync_linked_regs()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Preserve id of register in sync_linked_regs()\n\nsync_linked_regs() copies the id of known_reg to reg when propagating\nbounds of known_reg to reg using the off of known_reg, but when\nknown_reg was linked to reg like:\n\nknown_reg = reg ; both known_reg and reg get same id\nknown_reg += 4 ; known_reg gets off = 4, and its id gets BPF_ADD_CONST\n\nnow when a call to sync_linked_regs() happens, let's say with the following:\n\nif known_reg >= 10 goto pc+2\n\nknown_reg's new bounds are propagated to reg but now reg gets\nBPF_ADD_CONST from the copy.\n\nThis means if another link to reg is created like:\n\nanother_reg = reg ; another_reg should get the id of reg but\n assign_scalar_id_before_mov() sees\n BPF_ADD_CONST on reg and assigns a new id to it.\n\nAs reg has a new id now, known_reg's link to reg is broken. If we find\nnew bounds for known_reg, they will not be propagated to reg.\n\nThis can be seen in the selftest added in the next commit:\n\n0: (85) call bpf_get_prandom_u32#7 ; R0=scalar()\n1: (57) r0 &= 255 ; R0=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff))\n2: (bf) r1 = r0 ; R0=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) R1=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff))\n3: (07) r1 += 4 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=4,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff))\n4: (a5) if r1 < 0xa goto pc+4 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=10,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff))\n5: (bf) r2 = r0 ; R0=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=255) R2=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=255)\n6: (a5) if r1 < 0xe goto pc+2 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=14,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff))\n7: (35) if r0 >= 0xa goto pc+1 ; R0=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=9,var_off=(0x0; 0xf))\n8: (37) r0 /= 0\ndiv by zero\n\nWhen 4 is verified, r1's bounds are propagated to r0 but r0 also gets\nBPF_ADD_CONST (bug).\nWhen 5 is verified, r0 gets a new id (2) and its link with r1 is broken.\n\nAfter 6 we know r1 has bounds [14, 259] and therefore r0 should have\nbounds [10, 255], therefore the branch at 7 is always taken. But because\nr0's id was changed to 2, r1's new bounds are not propagated to r0.\nThe verifier still thinks r0 has bounds [6, 255] before 7 and execution\ncan reach div by zero.\n\nFix this by preserving id in sync_linked_regs() like off and subreg_def.","state":0,"publishedAt":"2026-05-27T12:17:51.127+00:00","modifiedAt":"2026-10-19T19:26:39.76+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"kernel/bpf/verifier.c\"\n ],\n \"versions\": [\n {\n \"version\": \"98d7ca374ba4b39e7535613d40e159f09ca14da2\",\n \"lessThan\": \"58059335e46537de682db84984f7716c813208c4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"98d7ca374ba4b39e7535613d40e159f09ca14da2\",\n \"lessThan\": \"92a8cb1806adefb263cf096eab6705705cf7eee1\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"98d7ca374ba4b39e7535613d40e159f09ca14da2\",\n \"lessThan\": \"65d114b5270b62aefb820ecd6c3b7caeea8f895d\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"98d7ca374ba4b39e7535613d40e159f09ca14da2\",\n \"lessThan\": \"af9e89d8dd39530c8bd14c33ddf6b502df1071b6\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"kernel/bpf/verifier.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.11\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.11\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.75\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.14\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.19.4\",\n \"lessThanOrEqual\": \"6.19.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.0\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/58059335e46537de682db84984f7716c813208c4","https://git.kernel.org/stable/c/92a8cb1806adefb263cf096eab6705705cf7eee1","https://git.kernel.org/stable/c/65d114b5270b62aefb820ecd6c3b7caeea8f895d","https://git.kernel.org/stable/c/af9e89d8dd39530c8bd14c33ddf6b502df1071b6"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-45933","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-45933","identifiers":["CVE-2026-45933"]},"retained":false,"historicalAffected":[]}],"coverage":[]}