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Fencer Vulns
medium 5.5

CVE-2009-3621 json

net/unix/af_unix.c in the Linux kernel 2.6.31.4 and earlier allows local users to cause a denial of service (system hang) by creating an ab…

published 2009-10-22 17 y ago modified 2026-06-16 4 mo ago also EUVD-2009-3602

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 62%
public exploits
1
Exploit-DB

Summary

net/unix/af_unix.c in the Linux kernel 2.6.31.4 and earlier allows local users to cause a denial of service (system hang) by creating an abstract-namespace AF_UNIX listening socket, performing a shutdown operation on this socket, and then performing a series of connect operations to this socket.

Patch / fix

  • kernel RHEL 4 2.6.9-89.0.18.EL
  • kernel-smp RHEL 4 2.6.9-89.0.18.EL
  • kernel-xenU RHEL 4 2.6.9-89.0.18.EL
  • kernel-hugemem RHEL 4 2.6.9-89.0.18.EL
  • kernel-largesmp RHEL 4 2.6.9-89.0.18.EL
  • kernel RHEL 5 2.6.18-164.9.1.el5
  • kernel-PAE RHEL 5 2.6.18-164.9.1.el5
  • kernel-xen RHEL 5 2.6.18-164.9.1.el5

red hat advisories RHSA-2009:1671RHSA-2009:1670RHSA-2009:1540

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2009-3621 updated cvss 4.9

kernel: AF_UNIX: Fix deadlock on connecting to shutdown socket

  • Red Hat MRG Realtime for RHEL 5 Server kernel-rt 2.6.24.7-137.el5rt, kernel-rt-trace 2.6.24.7-137.el5rt, kernel-rt-vanilla 2.6.24.7-137.el5rt, kernel-rt-debuginfo-common 2.6.24.7-137.el5rt
    fixed: vendor fix RHSA-2009:1540
  • Red Hat Enterprise Linux (v. 5 server) kernel 2.6.18-164.9.1.el5, kernel-PAE 2.6.18-164.9.1.el5, kernel-xen 2.6.18-164.9.1.el5, kernel-kdump 2.6.18-164.9.1.el5, kernel-debuginfo-common 2.6.18-164.9.1.el5
    fixed: vendor fix RHSA-2009:1670
  • Red Hat Enterprise Linux AS version 4 kernel 2.6.9-89.0.18.EL, kernel-smp 2.6.9-89.0.18.EL, kernel-xenU 2.6.9-89.0.18.EL, kernel-hugemem 2.6.9-89.0.18.EL, kernel-largesmp 2.6.9-89.0.18.EL
    fixed: vendor fix RHSA-2009:1671
  • Red Hat Enterprise Linux Desktop (v. 5 client) kernel 2.6.18-164.9.1.el5, kernel-PAE 2.6.18-164.9.1.el5, kernel-xen 2.6.18-164.9.1.el5, kernel-kdump 2.6.18-164.9.1.el5, kernel-debuginfo-common 2.6.18-164.9.1.el5
    fixed: vendor fix RHSA-2009:1670
  • Red Hat Enterprise Linux Desktop version 4 kernel 2.6.9-89.0.18.EL, kernel-smp 2.6.9-89.0.18.EL, kernel-xenU 2.6.9-89.0.18.EL, kernel-hugemem 2.6.9-89.0.18.EL, kernel-largesmp 2.6.9-89.0.18.EL Red Hat Enterprise Linux ES version 4 kernel 2.6.9-89.0.18.EL, kernel-smp 2.6.9-89.0.18.EL, kernel-xenU 2.6.9-89.0.18.EL, kernel-hugemem 2.6.9-89.0.18.EL, kernel-largesmp 2.6.9-89.0.18.EL Red Hat Enterprise Linux WS version 4 kernel 2.6.9-89.0.18.EL, kernel-smp 2.6.9-89.0.18.EL, kernel-xenU 2.6.9-89.0.18.EL, kernel-hugemem 2.6.9-89.0.18.EL, kernel-largesmp 2.6.9-89.0.18.EL
    fixed: vendor fix RHSA-2009:1671

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. Published
  2. First public exploit (EDB-10022)

Exploit prediction

0.99% chance of exploitation in the next 30 days, higher than 62% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-10022 Linux Kernel 2.6.31.4 - 'unix_stream_connect()' Local Denial of Service dos, 2009-11-10
  • openwall.com http://www.openwall.com/lists/oss-security/2009/10/19/2 referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com http://www.openwall.com/lists/oss-security/2009/10/19/4 referenced PoC, tagged "exploit" by a source, unverified
  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=529626 referenced PoC, tagged "exploit" by a source, unverified
  • patchwork.kernel.org http://patchwork.kernel.org/patch/54678/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.9 AV:L/AC:L/Au:N/C:N/I:N/A:C

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.