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Fencer Vulns
medium 5.5

CVE-2024-26741 json

dccp/tcp: Unhash sk from ehash for tb2 alloc failure after check_estalblished().

published 2024-04-03 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-24003

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 19%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

dccp/tcp: Unhash sk from ehash for tb2 alloc failure after check_estalblished().

syzkaller reported a warning [0] in inet_csk_destroy_sock() with no repro.

WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);

However, the syzkaller's log hinted that connect() failed just before the warning due to FAULT_INJECTION. [1]

When connect() is called for an unbound socket, we search for an available ephemeral port. If a bhash bucket exists for the port, we call __inet_check_established() or __inet6_check_established() to check if the bucket is reusable.

If reusable, we add the socket into ehash and set inet_sk(sk)->inet_num.

Later, we look up the corresponding bhash2 bucket and try to allocate it if it does not exist.

Although it rarely occurs in real use, if the allocation fails, we must revert the changes by check_established(). Otherwise, an unconnected socket could illegally occupy an ehash entry.

Note that we do not put tw back into ehash because sk might have already responded to a packet for tw and it would be better to free tw earlier under such memory presure.

[0]: WARNING: CPU: 0 PID: 350830 at net/ipv4/inet_connection_sock.c:1193 inet_csk_destroy_sock (net/ipv4/inet_connection_sock.c:1193) Modules linked in: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:inet_csk_destroy_sock (net/ipv4/inet_connection_sock.c:1193) Code: 41 5c 41 5d 41 5e e9 2d 4a 3d fd e8 28 4a 3d fd 48 89 ef e8 f0 cd 7d ff 5b 5d 41 5c 41 5d 41 5e e9 13 4a 3d fd e8 0e 4a 3d fd <0f> 0b e9 61 fe ff ff e8 02 4a 3d fd 4c 89 e7 be 03 00 00 00 e8 05 RSP: 0018:ffffc9000b21fd38 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000009e78 RCX: ffffffff840bae40 RDX: ffff88806e46c600 RSI: ffffffff840bb012 RDI: ffff88811755cca8 RBP: ffff88811755c880 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000009e78 R11: 0000000000000000 R12: ffff88811755c8e0 R13: ffff88811755c892 R14: ffff88811755c918 R15: 0000000000000000 FS: 00007f03e5243800(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32f21000 CR3: 0000000112ffe001 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: <TASK> ? inet_csk_destroy_sock (net/ipv4/inet_connection_sock.c:1193) dccp_close (net/dccp/proto.c:1078) inet_release (net/ipv4/af_inet.c:434) __sock_release (net/socket.c:660) sock_close (net/socket.c:1423) __fput (fs/file_table.c:377) __fput_sync (fs/file_table.c:462) __x64_sys_close (fs/open.c:1557 fs/open.c:1539 fs/open.c:1539) do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129) RIP: 0033:0x7f03e53852bb Code: 03 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 43 c9 f5 ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 c9 f5 ff 8b 44 RSP: 002b:00000000005dfba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f03e53852bb RDX: 0000000000000002 RSI: 0000000000000002 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000167c R10: 0000000008a79680 R11: 0000000000000293 R12: 00007f03e4e43000 R13: 00007f03e4e43170 R14: 00007f03e4e43178 R15: 00007f03e4e43170 </TASK>

[1]: FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 CPU: 0 PID: 350833 Comm: syz-executor.1 Not tainted 6.7.0-12272-g2121c43f88f5 #9 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:107 (discriminator 1)) should_fail_ex (lib/fault-inject.c:52 lib/fault-inject.c:153) should_failslab (mm/slub.c:3748) kmem_cache_alloc (mm/slub.c:3763 mm/slub.c:3842 mm/slub.c:3867) inet_bind2_bucket_create ---truncated---

Patch / fix

  • Linux Linux 6.1.80, 6.6.19, 6.7.7, 6.8
  • linux Debian 12 6.1.82-1
  • linux Debian 14, Debian 13 6.7.7-1

debian advisories DEBIAN-CVE-2024-26741

  • linux-raspi-realtime Ubuntu Pro Realtime 24.04 LTS 6.8.0-2002.2

ubuntu advisories UBUNTU-CVE-2024-26741

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-24.1
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-24.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-24.1
  • kernel-default-base Linux Micro 6.1, Linux Micro 6.0 6.4.0-24.1.21.4
  • kernel-livepatch-MICRO-6-0_Update_4 Linux Micro 6.1, Linux Micro 6.0 1-1.2
  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-22.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-22.1
  • kernel-livepatch-MICRO-6-0-RT_Update_4 Linux Micro 6.1, Linux Micro 6.0 1-1.1

suse advisories SUSE-SU-2025:20164-1SUSE-SU-2025:20247-1SUSE-SU-2025:20163-1SUSE-SU-2025:20246-1SUSE-SU-2024:4387-1SUSE-SU-2024:4318-1

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-2024-26741 updated cvss 5.5

kernel: dccp/tcp: Unhash sk from ehash for tb2 alloc failure after check_estalblished().

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

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

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling
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.