{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-38528", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:24.023Z", "datePublished": "2025-08-16T11:12:21.667Z", "dateUpdated": "2026-08-05T12:02:41.331Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:02:41.331Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject %p% format string in bprintf-like helpers\n\nstatic const char fmt[] = \"%p%\";\n bpf_trace_printk(fmt, sizeof(fmt));\n\nThe above BPF program isn't rejected and causes a kernel warning at\nruntime:\n\n Please remove unsupported %\\x00 in format string\n WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0\n\nThis happens because bpf_bprintf_prepare skips over the second %,\ndetected as punctuation, while processing %p. This patch fixes it by\nnot skipping over punctuation. %\\x00 is then processed in the next\niteration and rejected." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The only trigger is a locally loaded eBPF program invoking a bprintf-like helper (`bpf_trace_printk`, `bpf_trace_vprintk`, `bpf_snprintf`, `bpf_seq_printf`) via the `bpf()` syscall; the format string is attacker-authored at `BPF_PROG_LOAD` time and consumed in the calling task's own context. No remote peer or packet can supply a format string.\nAC:L - The attacker fully controls the constant format string, so `\"%p%\"` deterministically reaches the `WARN_ONCE` in `format_decode()` and `\"%p%s\"` deterministically desyncs `bpf_bprintf_prepare()` from `bstr_printf()` on the first call — no race, no timing window, no dependence on memory layout the attacker cannot influence.\nPR:L - Reaching the helpers requires CAP_BPF plus CAP_PERFMON (or CAP_SYS_ADMIN) rather than full root, and these are routinely granted to non-root eBPF observability/profiling service accounts and can be delegated into a user namespace via a BPF token (supported in all affected 6.9+ branches), so a low-privilege non-root actor suffices.\nUI:N - The attacker performs self-contained `bpf(BPF_PROG_LOAD)` and program-run/attach operations; no victim must mount a filesystem, open a file, or take any other action.\nS:U - The faulty parse, the warning, and the stale-memory read all occur in the kernel's own security authority within the calling task's context; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The prepare/print desync makes `bstr_printf()`'s `FORMAT_STATE_STR` `strlen()` and copy uninitialized bytes from the per-CPU `bpf_bprintf_buffers` (512-byte `bin_args` followed by the 1024-byte `buf`, and potentially past the struct into adjacent per-CPU memory) straight into the `bpf_snprintf` output buffer or trace ring buffer that the attacker reads; because `nocopy_fmt` stores raw unhashed 64-bit values there, this leaks unsanitized kernel pointers, on top of the KASLR-defeating backtrace the `WARN_ONCE` dumps to dmesg.\nI:N - All writes stay bounded — `nocopy_fmt` checks `tmp_buf_end - tmp_buf` before storing, and `bstr_printf()`/`string()` gate every store on `str < end` — so the bug under-fills the argument buffer rather than overflowing it; no kernel or user memory is modified out of bounds.\nA:H - `\"%p%\"` triggers `WARN_ONCE` at `lib/vsprintf.c:2807`, which becomes a full kernel panic on the widely deployed `panic_on_warn=1` used in hardened cloud, Android, and fuzzing configurations — exactly the crash syzbot reported — and the unbounded `strlen()` over per-CPU memory can additionally fault; even without `panic_on_warn` the splat taints the kernel and can trip health-check tooling into taking the node down." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/helpers.c" ], "versions": [ { "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915", "lessThan": "97303e541e12f1fea97834ec64b98991e8775f39", "status": "affected", "versionType": "git" }, { "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915", "lessThan": "61d5fa45ed13e42af14c7e959baba9908b8ee6d4", "status": "affected", "versionType": "git" }, { "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915", "lessThan": "e7be679124bae8cf4fa6e40d7e1661baddfb3289", "status": "affected", "versionType": "git" }, { "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915", "lessThan": "6952aeace93f8c9ea01849efecac24dd3152c9c9", "status": "affected", "versionType": "git" }, { "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915", "lessThan": "1c5f5fd47bbda17cb885fe6f03730702cd53d3f8", "status": "affected", "versionType": "git" }, { "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915", "lessThan": "f8242745871f81a3ac37f9f51853d12854fd0b58", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/helpers.c" ], "versions": [ { "version": "5.13", "status": "affected" }, { "version": "0", "lessThan": "5.13", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.190", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.147", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.100", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.40", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15.8", "lessThanOrEqual": "6.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "5.15.190" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.1.147" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.6.100" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.12.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.15.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/97303e541e12f1fea97834ec64b98991e8775f39" }, { "url": "https://git.kernel.org/stable/c/61d5fa45ed13e42af14c7e959baba9908b8ee6d4" }, { "url": "https://git.kernel.org/stable/c/e7be679124bae8cf4fa6e40d7e1661baddfb3289" }, { "url": "https://git.kernel.org/stable/c/6952aeace93f8c9ea01849efecac24dd3152c9c9" }, { "url": "https://git.kernel.org/stable/c/1c5f5fd47bbda17cb885fe6f03730702cd53d3f8" }, { "url": "https://git.kernel.org/stable/c/f8242745871f81a3ac37f9f51853d12854fd0b58" } ], "title": "bpf: Reject %p% format string in bprintf-like helpers", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:39:24.864Z" } } ] } }