{"apiVersion":"1.0","identifier":"CVE-2026-74633","description":"In the Linux kernel, the following vulnerability has been resolved: tracing: Fix NULL pointer dereference in module event cache removal A module-only event filter such as -:mod:foo- is cached with a NULL event_mod->match when foo has not been loaded. If a later write tries to remove a specific match from the same module, remove_cache_mod() passes the NULL cached match to strcmp(), causing a NULL pointer dereference. The issue can be reproduced from userspace: echo -:mod:trace_events_kunit_missing- > /sys/kernel/tracing/set_event echo -!foo_bar:mod:trace_events_kunit_missing- >> /sys/kernel/tracing/set_event The second write must be a concatenation (->>-) to not include O_TRUNC as that would cause ftrace_clear_events() to clear the cached modules lines. The crash was reproduced on x86_64 QEMU while KUnit workers contended on the event tracing path: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode RIP: 0010:strcmp+0x10/0x30 Call Trace: __ftrace_set_clr_event_nolock+0x373/0x4a0 ftrace_set_clr_event+0xf0/0x180 ftrace_event_write+0xdf/0x110 vfs_write+0xf6/0x440 ksys_write+0x68/0xe0 do_syscall_64+0xf9/0x540 entry_SYSCALL_64_after_hwframe+0x77/0x7f Check event_mod->match before comparing it, consistent with the existing NULL checks for the cached system and event fields. The mismatched removal continues to return -EINVAL; a broad cached module filter is removed with -!:mod:<module>-.","publishedAt":"2026-08-22T16:16:36","lastModifiedAt":"2026-08-22T16:16:36","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74633","cvssScore":null,"cvssVector":"Pending","epssProbability":0.00166,"riskScore":0,"affectedProduct":"Linux kernel","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-74633","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-74633","en":"https://www.redsauce.net/en/cves/CVE-2026-74633","fr":"https://www.redsauce.net/fr/cves/CVE-2026-74633","pt":"https://www.redsauce.net/pt/cves/CVE-2026-74633","de":"https://www.redsauce.net/de/cves/CVE-2026-74633","sk":"https://www.redsauce.net/sk/cves/CVE-2026-74633","el":"https://www.redsauce.net/el/cves/CVE-2026-74633"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-74633"}}