CVE-2025-23142sctp: detect and prevent references to a freed transport in sendmsg

Description

In the Linux kernel, the following vulnerability has been resolved: sctp: detect and prevent references to a freed transport in sendmsg sctp_sendmsg() re-uses associations and transports when possible by doing a lookup based on the socket endpoint and the message destination address, and then sctp_sendmsg_to_asoc() sets the selected transport in all the message chunks to be sent. There's a possible race condition if another thread triggers the removal of that selected transport, for instance, by explicitly unbinding an address with setsockopt(SCTP_SOCKOPT_BINDX_REM), after the chunks have been set up and before the message is sent. This can happen if the send buffer is full, during the period when the sender thread temporarily releases the socket lock in sctp_wait_for_sndbuf(). This causes the access to the transport data in sctp_outq_select_transport(), when the association outqueue is flushed, to result in a use-after-free read. This change avoids this scenario by having sctp_transport_free() signal the freeing of the transport, tagging it as "dead". In order to do this, the patch restores the "dead" bit in struct sctp_transport, which was removed in commit 47faa1e4c50e ("sctp: remove the dead field of sctp_transport"). Then, in the scenario where the sender thread has released the socket lock in sctp_wait_for_sndbuf(), the bit is checked again after re-acquiring the socket lock to detect the deletion. This is done while holding a reference to the transport to prevent it from being freed in the process. If the transport was deleted while the socket lock was relinquished, sctp_sendmsg_to_asoc() will return -EAGAIN to let userspace retry the send. The bug was found by a private syzbot instance (see the error report [1] and the C reproducer that triggers it [2]).

Timeline

Scores

EPSS (exploitation in 30 days)

0.23% · top 87% of all CVEs (14 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Affected products

• Linux · Linux

  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < 547762250220325d350d0917a7231480e0f4142b
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < 3257386be6a7eb8a8bfc9cbfb746df4eb4fc70e8
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < 0f7df4899299ce4662e5f95badb9dbc57cc37fa5
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < 7a63f4fb0efb4e69efd990cbb740a848679ec4b0
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < c6fefcb71d246baaf3bacdad1af7ff50ebcfe652
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < 9e7c37fadb3be1fc33073fcf10aa96d166caa697
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < 5bc83bdf5f5b8010d1ca5a4555537e62413ab4e2
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < 2e5068b7e0ae0a54f6cfd03a2f80977da657f1ee
  • affected df132eff463873e14e019a07f387b4d577d6d1f9 – < f1a69a940de58b16e8249dff26f74c8cc59b32be
  • affected 26e51e5287eed4d96ea66a3da95429f42940f013
  • affected 8b97e045bd6d37f96f161e4d371ae174148e1587
  • affected e044554e97e812eb257d073bcc130e0ea653858f
  • affected 8376fdc999be008f0e9918db52f1ed8c08f5a1c9
  • affected cd947138e8c31e8cfcd489c12e9b97271beb6e79
  • affected 3.18.128 – < 3.19
  • affected 4.4.166 – < 4.5
  • affected 4.9.142 – < 4.10
  • affected 4.14.85 – < 4.15
  • affected 4.19.6 – < 4.20

• Linux · Linux

  • affected 4.20
  • unaffected < 4.20
  • unaffected 5.4.293 – ≤ 5.4.*
  • unaffected 5.10.237 – ≤ 5.10.*
  • unaffected 5.15.181 – ≤ 5.15.*
  • unaffected 6.1.135 – ≤ 6.1.*
  • unaffected 6.6.88 – ≤ 6.6.*
  • unaffected 6.12.24 – ≤ 6.12.*
  • unaffected 6.13.12 – ≤ 6.13.*
  • unaffected 6.14.3 – ≤ 6.14.*
  • unaffected 6.15 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2025-13103 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2025-23142](https://cveledger.app/badge/CVE-2025-23142.svg)](https://cveledger.app/cve/CVE-2025-23142)

Record last updated 15 Oct 2026, 21:51 UTC.