{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21637", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.726Z", "datePublished": "2025-01-19T10:17:55.321Z", "dateUpdated": "2026-08-05T11:53:17.199Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:53:17.199Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: sysctl: udp_port: avoid using current->nsproxy\n\nAs mentioned in a previous commit of this series, using the 'net'\nstructure via 'current' is not recommended for different reasons:\n\n- Inconsistency: getting info from the reader's/writer's netns vs only\n from the opener's netns.\n\n- current->nsproxy can be NULL in some cases, resulting in an 'Oops'\n (null-ptr-deref), e.g. when the current task is exiting, as spotted by\n syzbot [1] using acct(2).\n\nThe 'net' structure can be obtained from the table->data using\ncontainer_of().\n\nNote that table->data could also be used directly, but that would\nincrease the size of this fix, while 'sctp.ctl_sock' still needs to be\nretrieved from 'net' structure." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Despite living in net/sctp/, the vulnerable function is a procfs sysctl ->proc_handler reachable only through local file I/O on /proc/sys/net/sctp/udp_port and local syscalls (acct(2), write(2)); no received SCTP or UDP packet ever reaches it.\nAC:L - Both trigger paths are fully deterministic and entirely attacker-driven — either unshare/open/SCM_RIGHTS/write for the netns-confusion path, or acct(2) plus `umount -l` plus process exit for the NULL deref — with no race, no victim state, and no memory-layout dependency.\nPR:L - An unprivileged user can reach the flaw via `unshare -Urn`, since cap_capable() grants the owner of a child user namespace CAP_NET_ADMIN over it (security/commoncap.c:92), letting a process still in the init netns write through the child's sysctl fd and have the handler act on init_net; no real root is needed for that path.\nUI:N - The attacker performs every step from its own cooperating processes — namespace creation, fd passing, the write, or its own exit — with no action required from any other user or administrator.\nS:U - The flawed code and the affected resources are both kernel network-namespace state within the same kernel security authority; no hypervisor, IOMMU, or VM boundary is crossed.\nC:N - The NULL+offset dereference faults before returning any data, and the read side of the netns confusion only reports the caller's own netns value for a world-readable (0644) setting, so no protected information is disclosed.\nI:H - The netns confusion lets an unprivileged local user write init_net.sctp.udp_port and drive sctp_udp_sock_stop()/sctp_udp_sock_start() on the host namespace, fully controlling whether and on which port the host kernel decapsulates SCTP from UDP — an attacker-chosen modification of protected host network state and a bypass of SCTP packet filtering.\nA:H - The NULL-ptr-deref oops fires inside do_exit() while acct->lock is held, wedging the exiting task with a stuck mutex and pinned mount and panicking outright on panic_on_oops builds; separately, the cross-netns write destroys the host's SCTP UDP tunnel sockets, severing SCTP-over-UDP connectivity." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sctp/sysctl.c" ], "versions": [ { "version": "046c052b475e7119b6a30e3483e2888fc606a2f8", "lessThan": "0a0966312ac3eedd7f5f2a766ed4702df39a9a65", "status": "affected", "versionType": "git" }, { "version": "046c052b475e7119b6a30e3483e2888fc606a2f8", "lessThan": "e919197fb8616331f5dc81e4c3cc3d12769cb725", "status": "affected", "versionType": "git" }, { "version": "046c052b475e7119b6a30e3483e2888fc606a2f8", "lessThan": "55627918febdf9d71107a1e68d1528dc591c9a15", "status": "affected", "versionType": "git" }, { "version": "046c052b475e7119b6a30e3483e2888fc606a2f8", "lessThan": "5b77d73f3be5102720fb685b9e6900e3500e1096", "status": "affected", "versionType": "git" }, { "version": "046c052b475e7119b6a30e3483e2888fc606a2f8", "lessThan": "c10377bbc1972d858eaf0ab366a311b39f8ef1b6", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sctp/sysctl.c" ], "versions": [ { "version": "5.11", "status": "affected" }, { "version": "0", "lessThan": "5.11", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.177", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.125", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.72", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.10", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "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": "5.11", "versionEndExcluding": "5.15.177" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.1.125" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.6.72" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.12.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0a0966312ac3eedd7f5f2a766ed4702df39a9a65" }, { "url": "https://git.kernel.org/stable/c/e919197fb8616331f5dc81e4c3cc3d12769cb725" }, { "url": "https://git.kernel.org/stable/c/55627918febdf9d71107a1e68d1528dc591c9a15" }, { "url": "https://git.kernel.org/stable/c/5b77d73f3be5102720fb685b9e6900e3500e1096" }, { "url": "https://git.kernel.org/stable/c/c10377bbc1972d858eaf0ab366a311b39f8ef1b6" } ], "title": "sctp: sysctl: udp_port: avoid using current->nsproxy", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2025-21637", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2025-10-01T19:54:10.551212Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-476", "description": "CWE-476 NULL Pointer Dereference" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T19:57:17.821Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:58:15.076Z" } } ] } }