{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-43403", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:56.007Z", "datePublished": "2026-05-08T14:21:44.204Z", "dateUpdated": "2026-08-05T12:27:47.212Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:27:47.212Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnsfs: tighten permission checks for ns iteration ioctls\n\nEven privileged services should not necessarily be able to see other\nprivileged service's namespaces so they can't leak information to each\nother. Use may_see_all_namespaces() helper that centralizes this policy\nuntil the nstree adapts." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable path is reached by a local `ioctl()` on an nsfs mount-namespace file descriptor, such as one obtained from `/proc/self/ns/mnt` or pidfd namespace ioctls. There is no network, adjacent, or physical attack path.\nAC:L - Triggering is deterministic: open a mount namespace fd and issue `NS_MNT_GET_NEXT` or `NS_MNT_GET_PREV`. There is no race or special memory-layout condition required.\nPR:L - The pre-fix check only required `CAP_SYS_ADMIN` in the target mount namespace's owning user namespace, which can be satisfied through user namespaces in plausible deployments. Under the higher-severity rule, this is Low rather than High.\nUI:N - No victim interaction is needed once the attacker has local execution and the relevant namespace capability. The attacker directly invokes the ioctl.\nS:C - The bug lets one namespace-confined service obtain file descriptors for other mount namespaces, bypassing the intended namespace visibility boundary. That can cross container or service isolation boundaries.\nC:H - The returned namespace fd and mount namespace id allow enumeration with `listmount()` and `statmount()`, exposing mount topology, paths, sources, options, and related metadata from another namespace. In plausible privileged-container scenarios, the fd can also enable `setns()` into the target mount namespace and expose sensitive filesystem contents.\nI:H - With the leaked mount namespace fd and the same namespace capabilities required by the vulnerable path, an attacker can plausibly `setns()` into another mount namespace and modify writable files or mount state there. This can compromise integrity across the namespace boundary.\nA:H - After obtaining and entering another mount namespace in a privileged scenario, the attacker can disrupt that namespace by altering or unmounting resources or damaging writable files. This can cause high availability impact to the affected service or container." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nsfs.c", "include/linux/ns_common.h", "kernel/nscommon.c" ], "versions": [ { "version": "a1d220d9dafa8d76ba60a784a1016c3134e6a1e8", "lessThan": "3376b345df155ca36d8611857b41ff7d5183fc38", "status": "affected", "versionType": "git" }, { "version": "a1d220d9dafa8d76ba60a784a1016c3134e6a1e8", "lessThan": "2f3dea284c761c890d676f77d5e55c0c496b4ef4", "status": "affected", "versionType": "git" }, { "version": "a1d220d9dafa8d76ba60a784a1016c3134e6a1e8", "lessThan": "0ad650e60150eda789deca5e78a6a09d26bf8fc9", "status": "affected", "versionType": "git" }, { "version": "a1d220d9dafa8d76ba60a784a1016c3134e6a1e8", "lessThan": "e6b899f08066e744f89df16ceb782e06868bd148", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nsfs.c", "include/linux/ns_common.h", "kernel/nscommon.c" ], "versions": [ { "version": "6.12", "status": "affected" }, { "version": "0", "lessThan": "6.12", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.78", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.20", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.9", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "6.12", "versionEndExcluding": "6.12.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "6.18.20" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "6.19.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3376b345df155ca36d8611857b41ff7d5183fc38" }, { "url": "https://git.kernel.org/stable/c/2f3dea284c761c890d676f77d5e55c0c496b4ef4" }, { "url": "https://git.kernel.org/stable/c/0ad650e60150eda789deca5e78a6a09d26bf8fc9" }, { "url": "https://git.kernel.org/stable/c/e6b899f08066e744f89df16ceb782e06868bd148" } ], "title": "nsfs: tighten permission checks for ns iteration ioctls", "x_generator": { "engine": "bippy-1.2.0" } } } }