{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21640", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.727Z", "datePublished": "2025-01-19T10:17:57.593Z", "dateUpdated": "2026-08-05T11:53:19.350Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:53:19.350Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: sysctl: cookie_hmac_alg: 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, as this is the only\nmember needed from the 'net' structure, but that would increase the size\nof this fix, to use '*data' everywhere 'net->sctp.sctp_hmac_alg' is\nused." } ], "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 - The buggy handler is only reachable through local interfaces — a write/read on /proc/sys/net/sctp/cookie_hmac_alg or an acct(2)-pinned file — never from received network data. No remote peer input reaches proc_sctp_do_hmac_alg().\nAC:L - Both paths are deterministic and fully attacker-controlled: the netns-confusion write is a plain unshare + SCM_RIGHTS + write(2) sequence with no race, and the acct(2) NULL deref triggers reliably every time the pidns reaper exits. No memory-layout or timing conditions outside the attacker's control.\nPR:L - The cross-namespace path needs only an unprivileged local user, since unprivileged user namespaces (default-enabled on Ubuntu/Debian/Fedora/Android) make the caller owner of the new userns and thus CAP_NET_ADMIN-equivalent over its netns, letting it drive a write that lands in init_net. Only the secondary acct(2) oops path additionally needs CAP_SYS_PACCT.\nUI:N - The attacker performs every step itself — unshare, open, fd passing, write, or acct(2) plus process exit. No victim action or cooperation is involved.\nS:U - The vulnerable component and the impacted resource are both the kernel under the same security authority; per kernel CNA convention namespace/privilege boundary crossings within the kernel are scored Unchanged rather than as a Changed-scope escape.\nC:N - The read path always returns the reader's own netns value, so no data crosses a security boundary, and the NULL dereference discloses no memory contents. There is no read primitive or information leak.\nI:H - An unprivileged user can make the handler write the initial network namespace's sctp_hmac_alg; setting it to \"none\" leaves sp->hmac NULL so sctp_unpack_cookie() jumps to no_hmac and skips signature verification entirely, disabling SCTP state-cookie authentication host-wide and enabling blind association spoofing. That is a serious loss of integrity for a security-relevant global setting.\nA:H - With current->nsproxy NULL during task exit the handler dereferences a NULL pointer, producing a kernel Oops (syzbot-confirmed) — a full panic on panic_on_oops systems and at minimum a task killed in the middle of do_exit with namespaces already torn down." } ] } ], "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": "3c68198e75111a905ac2412be12bf7b29099729b", "lessThan": "5599b212d2f4466e1832a94e9932684aaa364587", "status": "affected", "versionType": "git" }, { "version": "3c68198e75111a905ac2412be12bf7b29099729b", "lessThan": "03ca51faba2b017bf6c90e139434c4117d0afcdc", "status": "affected", "versionType": "git" }, { "version": "3c68198e75111a905ac2412be12bf7b29099729b", "lessThan": "86ddf8118123cb58a0fb8724cad6979c4069065b", "status": "affected", "versionType": "git" }, { "version": "3c68198e75111a905ac2412be12bf7b29099729b", "lessThan": "3cd0659deb9c03535fd61839e91d4d4d3e51ac71", "status": "affected", "versionType": "git" }, { "version": "3c68198e75111a905ac2412be12bf7b29099729b", "lessThan": "ad673e514b2793b8d5902f6ba6ab7e890dea23d5", "status": "affected", "versionType": "git" }, { "version": "3c68198e75111a905ac2412be12bf7b29099729b", "lessThan": "f0bb3935470684306e4e04793a20ac4c4b08de0b", "status": "affected", "versionType": "git" }, { "version": "3c68198e75111a905ac2412be12bf7b29099729b", "lessThan": "ea62dd1383913b5999f3d16ae99d411f41b528d4", "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": "3.8", "status": "affected" }, { "version": "0", "lessThan": "3.8", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.292", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.234", "lessThanOrEqual": "5.10.*", "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": "3.8", "versionEndExcluding": "5.4.292" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "5.10.234" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "5.15.177" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.1.125" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.6.72" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.12.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5599b212d2f4466e1832a94e9932684aaa364587" }, { "url": "https://git.kernel.org/stable/c/03ca51faba2b017bf6c90e139434c4117d0afcdc" }, { "url": "https://git.kernel.org/stable/c/86ddf8118123cb58a0fb8724cad6979c4069065b" }, { "url": "https://git.kernel.org/stable/c/3cd0659deb9c03535fd61839e91d4d4d3e51ac71" }, { "url": "https://git.kernel.org/stable/c/ad673e514b2793b8d5902f6ba6ab7e890dea23d5" }, { "url": "https://git.kernel.org/stable/c/f0bb3935470684306e4e04793a20ac4c4b08de0b" }, { "url": "https://git.kernel.org/stable/c/ea62dd1383913b5999f3d16ae99d411f41b528d4" } ], "title": "sctp: sysctl: cookie_hmac_alg: avoid using current->nsproxy", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:58:23.595Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-05-12T12:03:02.019Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 TM MFP - GNU/Linux subsystem", "versions": [ { "status": "affected", "version": "0", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html" } ] } ] } }