cbcvebase.
CVE-2009-3547
published 2009-11-04

CVE-2009-3547: Multiple race conditions in fs/pipe.c in the Linux kernel before 2.6.32-rc6 allow local users to cause a denial of service (NULL pointer dereference and system…

PriorityP271high7CVSS 3.1
AVLACHPRLUINSUCHIHAH
ITWEXPLOITVulnCheck KEV
Exploited in the wild
EPSS
4.89%
91.1th percentile
Multiple race conditions in fs/pipe.c in the Linux kernel before 2.6.32-rc6 allow local users to cause a denial of service (NULL pointer dereference and system crash) or gain privileges by attempting to open an anonymous pipe via a /proc/*/fd/ pathname.

Affected

27 ranges· showing 25
VendorProductVersion rangeFixed in
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
fedoraprojectfedora
linuxlinux_kernel<= 2.6.31.14
linuxlinux_kernel
novelllinux_desktop
opensuseopensuse
opensuseopensuse
redhatenterprise_linux_desktop
redhatenterprise_linux_desktop
redhatenterprise_linux_desktop
redhatenterprise_linux_eus
redhatenterprise_linux_eus
redhatenterprise_linux_server
redhatenterprise_linux_server
redhatenterprise_linux_server
redhatenterprise_linux_workstation
redhatenterprise_linux_workstation
redhatenterprise_linux_workstation
redhatmrg_realtime
susesuse_linux_enterprise_desktop
susesuse_linux_enterprise_server

Detection & IOCsextracted from sources · hover to see the quote

path/proc/*/fd/
path/proc/$OUT/fd/1
path/proc/%d/fd/4
path/proc/%d/fd/4
  • Exploit triggers by opening /proc/<pid>/fd/<n> on an anonymous pipe fd — monitor for processes repeatedly opening /proc/*/fd/* paths on pipe file descriptors, especially from unprivileged users.
  • Exploit pattern involves a race between rapid pipe() creation/close in one thread and concurrent open() of /proc/<pid>/fd/<n> in another — detect tight loops of pipe()+close() paired with /proc/*/fd/* open() calls from the same process.
  • Exploit maps a fake pipe_inode_info structure at NULL (address 0x0) via mmap(0, 0x1000, PROT_READ|PROT_EXEC|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, 0, 0) — detect mmap calls with MAP_FIXED at address 0 from unprivileged processes.
  • Exploit writes to /proc/<pid>/fd/1 to trigger the NULL pointer dereference — alert on write() or shell redirection targeting /proc/*/fd/* paths on pipe descriptors.
  • Check /boot/config* for CONFIG_PREEMPT, CONFIG_LOCKBREAK, or CONFIG_DEBUG_SPINLOCK as exploit notes these affect exploitability and structure layout.
  • Exploit notes single-processor machines with CONFIG_PREEMPT_NONE=y may not be exploitable — use kernel config as a triage factor when assessing exposure.
  • ·Vulnerability affects Linux kernel before 2.6.32-rc6; systems running 2.6.32-rc6 or later are not affected.
  • ·Exploit structure layouts differ across kernel sub-versions (2.6.0–2.6.10, 2.6.11–2.6.16, 2.6.17–2.6.19, 2.6.20–2.6.22, 2.6.23–2.6.31); detection/mitigation must account for the specific kernel version in use.
  • ·Exploit reliability is affected by kernel build options PREEMPT, LOCKBREAK, and DEBUG_SPINLOCK — structures must be modified accordingly, and CONFIG_PREEMPT_NONE on single-CPU machines may prevent exploitation.

CVSS provenance

nvdv3.17.0HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
nvdv2.06.9MEDIUMAV:L/AC:M/Au:N/C:C/I:C/A:C
vulncheck7.0HIGH
vendor_redhat7.0HIGH
vendor_ubuntu4.9MEDIUM
CVEs like this are exactly what “Exploited This Week” covers.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.