{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21638","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-12-29T08:45:45.727Z","datePublished":"2025-01-19T10:17:56.084Z","dateUpdated":"2026-08-05T11:53:18.276Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:53:18.276Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: sysctl: auth_enable: 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/, `proc_sctp_do_auth()` is a procfs sysctl ->proc_handler that no received SCTP packet, socket, or association path ever invokes; it is reached only through local file I/O on /proc/sys/net/sctp/auth_enable and local syscalls (write(2), acct(2)).\nAC:L - Both trigger paths are fully deterministic and entirely attacker-scripted — unshare/open/SCM_RIGHTS/write for the netns-confusion path, or acct(2) plus lazy umount plus process exit for the NULL deref — with no race, no victim state, and no memory-layout dependency.\nPR:L - An unprivileged local user reaches the flaw via unprivileged user namespaces (default-enabled on Ubuntu/Debian/Fedora/Android), 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; only the secondary acct(2) oops path additionally needs CAP_SYS_PACCT.\nUI:N - The attacker performs every step from its own cooperating processes — namespace creation, fd passing, the write, or acct(2) and 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 under the same kernel security authority; per kernel CNA convention namespace boundary crossings inside the kernel are scored Unchanged, and no hypervisor, IOMMU, or VM boundary is involved.\nC:N - The NULL+0x28 dereference faults before any data is returned to userspace, 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.auth_enable and directly mutate the host control socket's endpoint (sctp_sk(net->sctp.ctl_sock)->ep->auth_enable); clearing it makes every newly created host endpoint skip sctp_auth_init() and stop negotiating RFC 4895 AUTH, disabling SCTP chunk authentication host-wide — an attacker-chosen modification of protected host state and a bypass of a security control.\nA:H - The NULL-ptr-deref oopses inside do_exit() after exit_task_namespaces() while acct->lock is held under mnt_pin_kill(), wedging the task mid-teardown with a permanently held mutex and pinned mount, and panicking outright on the panic_on_oops builds common in embedded, automotive, and hardened deployments."}]}],"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":"b14878ccb7fac0242db82720b784ab62c467c0dc","lessThan":"cf387cdebfaebae228dfba162f94c567a67610c3","status":"affected","versionType":"git"},{"version":"b14878ccb7fac0242db82720b784ab62c467c0dc","lessThan":"dc583e7e5f8515ca489c0df28e4362a70eade382","status":"affected","versionType":"git"},{"version":"b14878ccb7fac0242db82720b784ab62c467c0dc","lessThan":"bd2a2939423566c654545fa3e96a656662a0af9e","status":"affected","versionType":"git"},{"version":"b14878ccb7fac0242db82720b784ab62c467c0dc","lessThan":"1b67030d39f2b00f94ac1f0af11ba6657589e4d3","status":"affected","versionType":"git"},{"version":"b14878ccb7fac0242db82720b784ab62c467c0dc","lessThan":"7ec30c54f339c640aa7e49d7e9f7bbed6bd42bf6","status":"affected","versionType":"git"},{"version":"b14878ccb7fac0242db82720b784ab62c467c0dc","lessThan":"c184bc621e3cef03ac9ba81a50dda2dae6a21d36","status":"affected","versionType":"git"},{"version":"b14878ccb7fac0242db82720b784ab62c467c0dc","lessThan":"15649fd5415eda664ef35780c2013adeb5d9c695","status":"affected","versionType":"git"},{"version":"e5eae4a0511241959498b180fa0df0d4f1b11b9c","status":"affected","versionType":"git"},{"version":"88830f227a1f96e44d82ddfcb0cc81d517ec6dd8","status":"affected","versionType":"git"},{"version":"3938b0336a93fa5faa242dc9e5823ac69df9e066","status":"affected","versionType":"git"},{"version":"3.10.41","lessThan":"3.11","status":"affected","versionType":"semver"},{"version":"3.12.21","lessThan":"3.13","status":"affected","versionType":"semver"},{"version":"3.14.5","lessThan":"3.15","status":"affected","versionType":"semver"}]},{"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":"3.15","status":"affected"},{"version":"0","lessThan":"3.15","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":"3.15","versionEndExcluding":"5.4.292"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"5.10.234"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"5.15.177"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.1.125"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.6.72"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.12.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15","versionEndExcluding":"6.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10.41"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.12.21"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14.5"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/cf387cdebfaebae228dfba162f94c567a67610c3"},{"url":"https://git.kernel.org/stable/c/dc583e7e5f8515ca489c0df28e4362a70eade382"},{"url":"https://git.kernel.org/stable/c/bd2a2939423566c654545fa3e96a656662a0af9e"},{"url":"https://git.kernel.org/stable/c/1b67030d39f2b00f94ac1f0af11ba6657589e4d3"},{"url":"https://git.kernel.org/stable/c/7ec30c54f339c640aa7e49d7e9f7bbed6bd42bf6"},{"url":"https://git.kernel.org/stable/c/c184bc621e3cef03ac9ba81a50dda2dae6a21d36"},{"url":"https://git.kernel.org/stable/c/15649fd5415eda664ef35780c2013adeb5d9c695"}],"title":"sctp: sysctl: auth_enable: 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":"2025-11-03T20:58:17.877Z"}},{"x_adpType":"supplier","providerMetadata":{"orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","shortName":"siemens-SADP","dateUpdated":"2026-05-12T12:02:58.938Z"},"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"}]}]}}