{"id":"CVE-2025-21639","title":"sctp: sysctl: rto_min/max: avoid using current->nsproxy","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: sysctl: rto_min/max: avoid using current->nsproxy\n\nAs mentioned in a previous commit of this series, using the 'net'\nstructure via 'current' is not recommended fo…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"adp","vendor":"Linux","product":"Linux","affected":["Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < c8d179f3b1c1d60bf4484f50aa67b4c70f91bff9","Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 246428bfb9e7db15c5cd08e1d0eca41b65af2b06","Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 0f78f09466744589e420935e646ae78212a38290","Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 4059507e34aa5fe0fa9fd5b2b5f0c8b26ab2d482","Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < dc9d0e3cfd16f66fbf0862857c6b391c8613ca9f","Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < c87f1f6ade56c711f8736901e330685b453e420e","Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 9fc17b76fc70763780aa78b38fcf4742384044a5","Linux 3.13"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2025-10-01T19:54:07.301315Z"},"published":"2025-01-19","updated":"2026-10-15","sourceUpdated":"2026-10-15T01:02:42.114Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-21639","references":[{"url":"https://git.kernel.org/stable/c/c8d179f3b1c1d60bf4484f50aa67b4c70f91bff9"},{"url":"https://git.kernel.org/stable/c/246428bfb9e7db15c5cd08e1d0eca41b65af2b06"},{"url":"https://git.kernel.org/stable/c/0f78f09466744589e420935e646ae78212a38290"},{"url":"https://git.kernel.org/stable/c/4059507e34aa5fe0fa9fd5b2b5f0c8b26ab2d482"},{"url":"https://git.kernel.org/stable/c/dc9d0e3cfd16f66fbf0862857c6b391c8613ca9f"},{"url":"https://git.kernel.org/stable/c/c87f1f6ade56c711f8736901e330685b453e420e"},{"url":"https://git.kernel.org/stable/c/9fc17b76fc70763780aa78b38fcf4742384044a5"}],"tags":["cve.org"],"epss":0.00229,"epssPercentile":0.13594,"ingestedAt":"2026-10-15T04:46:37.352Z","slug":"CVE-2025-21639","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsctp: sysctl: rto_min/max: 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.rto_min/max' is used.\n\n## Affected\n\n- `Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < c8d179f3b1c1d60bf4484f50aa67b4c70f91bff9`\n- `Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 246428bfb9e7db15c5cd08e1d0eca41b65af2b06`\n- `Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 0f78f09466744589e420935e646ae78212a38290`\n- `Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 4059507e34aa5fe0fa9fd5b2b5f0c8b26ab2d482`\n- `Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < dc9d0e3cfd16f66fbf0862857c6b391c8613ca9f`\n- `Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < c87f1f6ade56c711f8736901e330685b453e420e`\n- `Linux >= 4f3fdf3bc59cafd14c3bc2c2369efad34c7aa8b5 < 9fc17b76fc70763780aa78b38fcf4742384044a5`\n- `Linux 3.13`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}