{"id":"CVE-2026-64496","title":"iio: event: Fix event FIFO reset race","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\niio: event: Fix event FIFO reset race\n\n`iio_event_getfd()` creates the event file descriptor with\n`anon_inode_getfd()`, which allocates a new fd, creates the anonymous\n…","severity":"high","cvss":7.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 9dc84ba4be5bbeb29ee49efe6cea2cb32c461424","Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < d16a702ca7d29c0b7a9b509339d1b044a1cadb32","Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < a13ef1adbc62085b21b546b07b0be7e2fbf52150","Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 0d4a646d7f87ea3625fafe387043fddc6a2f5e7f","Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 72c6aa8e0d74eab91b8694cde97dec088c248fee","Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 9edefd4c56bee3fe331e0355d1f10a533134999d","Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < f187dc5a4c4846ffa07d9bda6e760837ed005574","Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < af791d295737ea6b6ff2c8d8488462a49c14af01","Linux 3.15"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-10-16T15:41:26.474365Z"},"published":"2026-07-25","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:42:38.605Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64496","references":[{"url":"https://git.kernel.org/stable/c/9dc84ba4be5bbeb29ee49efe6cea2cb32c461424"},{"url":"https://git.kernel.org/stable/c/d16a702ca7d29c0b7a9b509339d1b044a1cadb32"},{"url":"https://git.kernel.org/stable/c/a13ef1adbc62085b21b546b07b0be7e2fbf52150"},{"url":"https://git.kernel.org/stable/c/0d4a646d7f87ea3625fafe387043fddc6a2f5e7f"},{"url":"https://git.kernel.org/stable/c/72c6aa8e0d74eab91b8694cde97dec088c248fee"},{"url":"https://git.kernel.org/stable/c/9edefd4c56bee3fe331e0355d1f10a533134999d"},{"url":"https://git.kernel.org/stable/c/f187dc5a4c4846ffa07d9bda6e760837ed005574"},{"url":"https://git.kernel.org/stable/c/af791d295737ea6b6ff2c8d8488462a49c14af01"}],"tags":["cve.org"],"epss":0.00126,"epssPercentile":0.02066,"ingestedAt":"2026-10-16T17:24:46.823Z","slug":"CVE-2026-64496","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\niio: event: Fix event FIFO reset race\n\n`iio_event_getfd()` creates the event file descriptor with\n`anon_inode_getfd()`, which allocates a new fd, creates the anonymous\nfile and installs it in the process fd table before returning to the\ncaller.\n\nThe IIO code resets the event FIFO after `anon_inode_getfd()` has returned,\nbut before `IIO_GET_EVENT_FD_IOCTL` has copied the fd number to userspace.\nBut since fd tables are shared between threads, another thread can guess\nthe newly allocated fd number and issue a `read()` on it as soon as the fd\nhas been installed.\n\nThis means the `kfifo_to_user()` in `iio_event_chrdev_read()` can run in\nparallel with the `kfifo_reset_out()` in `iio_event_getfd()`.\n\nThe kfifo documentation says that `kfifo_reset_out()` is only safe when it\nis called from the reader thread and there is only one concurrent reader.\nOtherwise it is dangerous and must be handled in the same way as\n`kfifo_reset()`.\n\nIf that happens, `kfifo_to_user()` can advance the FIFO `out` index based\non state from before the reset, after the reset has already moved the `out`\nindex to the current `in` index. That can leave the FIFO with an `out`\nindex past the `in` index. A later `read()` can then see an underflowed\nFIFO length and copy more data than the event FIFO buffer contains. This\ncan result in an out-of-bounds read and leak adjacent kernel memory to\nuserspace.\n\nMove the FIFO reset before `anon_inode_getfd()`. At that point the event fd is\nmarked busy, but the new fd has not been installed yet, so userspace cannot\naccess it while the FIFO is reset.\n\n## Affected\n\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 9dc84ba4be5bbeb29ee49efe6cea2cb32c461424`\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < d16a702ca7d29c0b7a9b509339d1b044a1cadb32`\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < a13ef1adbc62085b21b546b07b0be7e2fbf52150`\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 0d4a646d7f87ea3625fafe387043fddc6a2f5e7f`\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 72c6aa8e0d74eab91b8694cde97dec088c248fee`\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < 9edefd4c56bee3fe331e0355d1f10a533134999d`\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < f187dc5a4c4846ffa07d9bda6e760837ed005574`\n- `Linux >= b91accafbb1031b80d22ad83576877ff2f8b4774 < af791d295737ea6b6ff2c8d8488462a49c14af01`\n- `Linux 3.15`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":39.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}