---
cve: "CVE-2026-89477"
severity: "HIGH"
cvss: 7.5
epss: "51%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-09-11 20:19:29"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-18T17:46:00+02:00"
---

# CVE-2026-89477

> 7.5 HIGH

## Beschreibung

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

sctp: fix NULL deref on untransmitted RECONF completion

sctp_process_strreset_outreq(), sctp_process_strreset_addstrm_out() and
sctp_process_strreset_resp() complete a pending stream reconfiguration
request by stopping the reconf timer on the transport it was sent on:

	t = asoc->strreset_chunk->transport;
	if (timer_delete(&t->reconf_timer))
		sctp_transport_put(t);

chunk->transport is assigned by __sctp_packet_append_chunk() when the
chunk is appended to an outbound packet, and sctp_outq_flush_ctrl() arms
the reconf timer at that same point. A request already published in
asoc->strreset_chunk but not yet transmitted has neither, so completing
it dereferences NULL.

Two ways to get there. sctp_send_asconf_del_ip() sets
asoc->src_out_of_asoc_ok without sending anything when the address being
removed is the association's last one, and sctp_outq_flush_ctrl() then
leaves every non-ASCONF control chunk queued; as only
sctp_process_asconf_ack() clears that flag, it persists. An unprivileged
process that removes such an address and then asks for a stream reset
panics the kernel from softirq. A peer needs neither ASCONF nor local
help: sctp_cmd_interpreter() uncorks the outqueue only once the whole
packet has been processed, so a reply built while walking a RECONF chunk
stays untransmitted for the rest of that walk, and one RECONF chunk
carrying [Incoming SSN Reset Request, Outgoing SSN Reset Request,
Response] -- or two RECONF chunks in one packet -- reaches the same
dereference.

  KASAN: null-ptr-deref in range [0x00000000000001e8-0x00000000000001ef]
  RIP: 0010:timer_delete+0x67/0x110
  Call Trace:
   
   sctp_process_strreset_addstrm_out (net/sctp/stream.c:832)
   sctp_sf_do_reconf (net/sctp/sm_statefuns.c:4212)
   sctp_do_sm (net/sctp/sm_sideeffect.c:1172)
   sctp_assoc_bh_rcv (net/sctp/associola.c:1044)
   sctp_rcv (net/sctp/input.c:243)
   ip_local_deliver (net/ipv4/ip_input.c:262)
   process_backlog (net/core/dev.c:6680)
   

A response can only acknowledge a request that was actually sent, so do
not match asoc->strreset_chunk while chunk->transport is NULL. Guarding
the lookup covers all three completion sites.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 5.10.270
- Kernel ≥ 5.15.221
- Kernel ≥ 6.1.188
- Kernel ≥ 6.6.157
- Kernel ≥ 6.12.109
- Kernel ≥ 6.18.50
- Kernel ≥ 7.2.4

## Referenzen

- <https://git.kernel.org/stable/c/79ff751311e80fa0370007e46a79a6d601685e75>
- <https://git.kernel.org/stable/c/53141db979687eae7dc6d29414cefc77034f967e>
- <https://git.kernel.org/stable/c/68891125af5a5dfbca728809a16637a869bbe0df>
- <https://git.kernel.org/stable/c/b2d6d873b4dfb5b84194061c4b40a1cd85b92ca4>
- <https://git.kernel.org/stable/c/77ea60f2d24002c308f224db44a4542c466489af>
- <https://git.kernel.org/stable/c/25419f516ea84b1e7d3d55aae5215ac86ece0c66>
- <https://git.kernel.org/stable/c/0ee697defc0594f1da810ed75d9d643fb46f5318>
- <https://git.kernel.org/stable/c/2db9bfa3e27bdea15e05ea70b56bad3d21e570ec>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-89477) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_