{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2023-54139", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-24T13:02:52.522Z", "datePublished": "2025-12-24T13:06:54.094Z", "dateUpdated": "2026-08-05T09:17:34.267Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T09:17:34.267Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/user_events: Ensure write index cannot be negative\n\nThe write index indicates which event the data is for and accesses a\nper-file array. The index is passed by user processes during write()\ncalls as the first 4 bytes. Ensure that it cannot be negative by\nreturning -EINVAL to prevent out of bounds accesses.\n\nUpdate ftrace self-test to ensure this occurs properly." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerability is reached only through local file operations — `ioctl()`/`write()`/`writev()` on the tracefs file `/sys/kernel/tracing/user_events_data`. There is no network or remote-peer data path into `user_events_write_core()`.\nAC:L - Triggering is fully deterministic — the attacker registers an event, then writes a payload whose first 4 bytes are a negative integer, and the signed comparison `idx < refs->count` is bypassed every time. No race, timing window, or condition outside the attacker's control is involved, and the attacker can freely groom the slab to influence what the OOB read returns.\nPR:L - The registration ioctl and the write path contain no capability checks; the only gate is write access to the tracefs `user_events_data` file, which this feature exists specifically to grant to ordinary unprivileged applications (via tracefs `gid=` mounts or relaxed permissions in tracing-enabled deployments). An unprivileged local user with the intended tracing access can trigger it, so no administrative privilege is needed.\nUI:N - The attacker performs the entire sequence — open, `DIAG_IOCSREG`, then a `writev()` with a negative index — within their own process. No victim action, mount, or interaction of any kind is required.\nS:U - The out-of-bounds access and resulting type confusion occur entirely within the kernel's own memory and security authority. There is no crossing of a VM, IOMMU, or sandbox boundary — this is a standard local kernel compromise.\nC:H - A negative index yields a pointer-sized out-of-bounds read anywhere within roughly 16 GB below the `user_event_refs` allocation, and the resulting bogus `struct user_event *` is dereferenced to read `min_size`, `tracepoint`, and `call` fields, whose contents are then emitted into trace/perf buffers readable by the attacker. This constitutes an effectively arbitrary kernel-memory read primitive.\nI:H - The OOB-read value is used as a `struct user_event *` and reaches `probe_func = probe_func_ptr->func; probe_func(user, ...)`, an indirect call through an attacker-influenced pointer chain. Combined with heap grooming of the small `kmalloc` slab, this gives type confusion escalating to control-flow hijack and arbitrary kernel writes.\nA:H - Even without any exploitation effort, indexing arbitrarily far below the allocation and dereferencing the resulting garbage pointer reliably produces a kernel oops or panic. The fault is trivially and repeatedly reproducible by an unprivileged process, making it a dependable local denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/trace/trace_events_user.c", "tools/testing/selftests/user_events/ftrace_test.c" ], "versions": [ { "version": "7f5a08c79df35e68f1a43033450c5050f12bc155", "lessThan": "0489c2b2c3104b89f078dbcec8c744dfc157d3e9", "status": "affected", "versionType": "git" }, { "version": "7f5a08c79df35e68f1a43033450c5050f12bc155", "lessThan": "4fe46b5adf18e3dc606e62c9e6a0413398a17572", "status": "affected", "versionType": "git" }, { "version": "7f5a08c79df35e68f1a43033450c5050f12bc155", "lessThan": "fa7f2f5d1739452280c22727c4384a52b72ab5de", "status": "affected", "versionType": "git" }, { "version": "7f5a08c79df35e68f1a43033450c5050f12bc155", "lessThan": "cd98c93286a30cc4588dfd02453bec63c2f4acf4", "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/trace/trace_events_user.c", "tools/testing/selftests/user_events/ftrace_test.c" ], "versions": [ { "version": "5.18", "status": "affected" }, { "version": "0", "lessThan": "5.18", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.28", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.2.15", "lessThanOrEqual": "6.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.3.2", "lessThanOrEqual": "6.3.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.4", "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": "5.18", "versionEndExcluding": "6.1.28" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.2.15" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.3.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.4" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0489c2b2c3104b89f078dbcec8c744dfc157d3e9" }, { "url": "https://git.kernel.org/stable/c/4fe46b5adf18e3dc606e62c9e6a0413398a17572" }, { "url": "https://git.kernel.org/stable/c/fa7f2f5d1739452280c22727c4384a52b72ab5de" }, { "url": "https://git.kernel.org/stable/c/cd98c93286a30cc4588dfd02453bec63c2f4acf4" } ], "title": "tracing/user_events: Ensure write index cannot be negative", "x_generator": { "engine": "bippy-1.2.0" } } } }