{"id":"CVE-2026-98969","title":"net/sched: em_text: reject unterminated algo before autoload","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: em_text: reject unterminated algo before autoload\n\nThis is a follow-up to commit 9c572a83037a (\"net/sched: fix potential\nstack infoleak in em_text_dump()\"), …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < 00bcc303000bac524d62eed054d77372b38ace0f","Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < 22182f91c6703af6e9832cffe6d22b381031cb5a","Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < 85e5512369d4fe6e5f2c43712d9f9e01d4ae8437","Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < b627c6ba20be20334338229b4820baacb9d96826","Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < c9728fcf2e7fb4a7a8d08ebd9524c3b02ae1a021","Linux 2.6.13"],"published":"2026-10-23","updated":"2026-10-23","sourceUpdated":"2026-10-23T12:19:42.012Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98969","references":[{"url":"https://git.kernel.org/stable/c/00bcc303000bac524d62eed054d77372b38ace0f"},{"url":"https://git.kernel.org/stable/c/22182f91c6703af6e9832cffe6d22b381031cb5a"},{"url":"https://git.kernel.org/stable/c/85e5512369d4fe6e5f2c43712d9f9e01d4ae8437"},{"url":"https://git.kernel.org/stable/c/b627c6ba20be20334338229b4820baacb9d96826"},{"url":"https://git.kernel.org/stable/c/c9728fcf2e7fb4a7a8d08ebd9524c3b02ae1a021"}],"tags":["cve.org"],"ingestedAt":"2026-10-23T13:24:55.551Z","slug":"CVE-2026-98969","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: em_text: reject unterminated algo before autoload\n\nThis is a follow-up to commit 9c572a83037a (\"net/sched: fix potential\nstack infoleak in em_text_dump()\"), which zero-initialised the dump-side\nstruct. Sashiko pointed at a pre-existing bug that exposed the change-side\ninput-validation gap open.\n\nem_text_change() casts the raw netlink attribute payload to struct\ntcf_em_text and passes conf->algo, a 16-byte array with no enforced NUL\nterminator, to textsearch_prepare().  On the TS_AUTOLOAD retry\ntextsearch_prepare() calls request_module(\"ts_%s\", algo); vsnprintf()\nwalks %s until it finds a NUL, so an algo[] with no NUL reads past the\narray into the adjacent struct fields and payload and feeds those bytes\nto the usermode helper command line.  This is an out-of-bounds read and\na kernel memory disclosure.\n\nReject the attribute when no NUL exists within TC_EM_TEXT_ALGOSIZ bytes,\nmatching the check xt_string has had since 3ab720881b6e.\n\nConditions to recreate the bug:\n- CAP_NET_ADMIN on the target netns (namespace-local via unshare -Urn\n  is enough)\n- install clsact on an interface, then add a basic filter with one text\n  ematch whose algo[] is 16 bytes with no NUL (e.g. \"A\"*16) and\n  pattern_len at least 1\n- the add fails with -ENOENT and the kernel invokes modprobe with a\n  module name made of \"ts_\" plus the 16 bytes and the adjacent payload\n\n## Affected\n\n- `Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < 00bcc303000bac524d62eed054d77372b38ace0f`\n- `Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < 22182f91c6703af6e9832cffe6d22b381031cb5a`\n- `Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < 85e5512369d4fe6e5f2c43712d9f9e01d4ae8437`\n- `Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < b627c6ba20be20334338229b4820baacb9d96826`\n- `Linux >= d675c989ed2d4ba23dff615330b04371aea83534 < c9728fcf2e7fb4a7a8d08ebd9524c3b02ae1a021`\n- `Linux 2.6.13`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}