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.
References
Configurations
No configuration.
History
31 Oct 2026, 13:17
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.8 |
30 Oct 2026, 13:21
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
28 Oct 2026, 11:17
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-10-28 11:17
Updated : 2026-10-31 13:17
NVD link : CVE-2026-99203
Mitre link : CVE-2026-99203
CVE.ORG link : CVE-2026-99203
JSON object : View
Products Affected
No product.
CWE
No CWE.
