# CVE-2026-89478

## Summary

- **CVE ID:** CVE-2026-89478
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 14, 2026

## Description

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

sctp: drop a chunk if its transport was removed

sctp_rcv() resolves the transport once per packet and leaves it in
chunk->transport. The lookup reference, or the one sctp_add_backlog() takes
if the socket is owned by userspace, keeps it around until the chunk has
been processed.

An authenticated ASCONF DEL-IP can remove it in the meantime.
sctp_assoc_rm_peer() takes the transport out of the association and calls
sctp_transport_free(), which tags it dead and drops the reference the
association held. There is a window on both paths: the packet can sit on
the socket backlog, and on the direct path the lookup completes before
bh_lock_sock().

The DATA chunk in that packet puts the removed transport back into
asoc->peer.last_data_from. Once the packet is done that reference goes
away and the transport is freed by RCU, so the next delayed SACK carries
the pointer into the SACK chunk and sctp_outq_select_transport() reads the
freed transport's state.

Drop the chunk in sctp_inq_push(), next to the existing rcvr->dead check.
Both paths reach it with the association's socket lock held. The peer
retransmits it.

## Affected Products

- Linux — Linux (1da177e4c3f41524e886b7f1b8a0c1fc7321cac2)
- Linux — Linux (2.6.12)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)
- Linux — Linux (5.10.270)
- Linux — Linux (5.15.221)
- Linux — Linux (6.1.188)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/c6c86a5e62a4fec36692ddd64b9144b660f71f96)
- [CNA](https://git.kernel.org/stable/c/1035bdef1efb9b1076d1a57b81e08c637ff08ecc)
- [CNA](https://git.kernel.org/stable/c/3537961df2163258bddc230db0e18dc14e925ea6)
- [CNA](https://git.kernel.org/stable/c/03a9d10ecf71f54b2af8020935f2033d4a132be5)
- [CNA](https://git.kernel.org/stable/c/3fc072e7cb4a0ff251d13cfc2d24f62489cd9386)
- [CNA](https://git.kernel.org/stable/c/d7cb5ad832095dc4becfdb2a36007ffd50e49fb0)
- [CNA](https://git.kernel.org/stable/c/0422b092a3d43ca462932ff9f747731ca078d1d4)
- [CNA](https://git.kernel.org/stable/c/928fd7920ba37cc5637a211b9be979083413a2fa)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.52%
- **EPSS Percentile:** 43.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._