{"apiVersion":"1.0","identifier":"CVE-2026-99203","description":"In the Linux kernel, the following vulnerability has been resolved: pipe: preserve existing fasync readers on writer setup failure F_SETFL and FIOASYNC decide whether to invoke ->fasync() before pipe_fasync() takes pipe->mutex. Two enables of one O_RDWR FIFO can therefore both enter the callback. fasync_helper() allocates before checking for an existing entry. If the first enable installs both entries, a second enable can update the reader entry and then fail the allocation for the writer entry. The error path removes the pre-existing reader entry, clearing FASYNC while the writer entry remains registered. __fput() then skips ->fasync(), so a later pipe notification can dereference the freed file or its f_owner. An unprivileged memory-pressure reproducer triggers a KASAN slab-use-after-free in send_sigio() through this path. Keep the reader helper-s result and undo the registration only if this call added it. The pipe mutex serializes changes to both lists, so a failed new registration still removes its reader, while a failed duplicate preserves the existing registrations and FASYNC. Successful duplicate enables continue to update fa_fd as before.","publishedAt":"2026-10-28T11:17:41","lastModifiedAt":"2026-10-31T13:17:59","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-99203","cvssScore":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","epssProbability":0.00121,"riskScore":0.79,"affectedProduct":"Linux kernel","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-99203","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-99203","en":"https://www.redsauce.net/en/cves/CVE-2026-99203","fr":"https://www.redsauce.net/fr/cves/CVE-2026-99203","pt":"https://www.redsauce.net/pt/cves/CVE-2026-99203","de":"https://www.redsauce.net/de/cves/CVE-2026-99203","sk":"https://www.redsauce.net/sk/cves/CVE-2026-99203","el":"https://www.redsauce.net/el/cves/CVE-2026-99203"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-99203"}}