EUVD-2026-76384
GHSA-47r2-m88p-rgjm
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Needs authenticated SCTP association peer (PR:L) and winning a tight race (AC:H); impact is a use-after-free crash (A:H) with no clear C/I compromise.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
Lifecycle Timeline
5DescriptionCVE.org
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.
AnalysisAI
Use-after-free in the Linux kernel SCTP stack (net/sctp) allows a peer in an established, authenticated SCTP association to trigger a stale transport reference by removing an IP address via ASCONF DEL-IP while an inbound packet is still being processed. sctp_rcv() caches the resolved transport in chunk->transport, but a concurrent sctp_assoc_rm_peer()/sctp_transport_free() can free it during the backlog window or before bh_lock_sock(), after which a delayed SACK causes sctp_outq_select_transport() to read freed memory. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Requires SCTP to be in use on the target and an established, authenticated SCTP association in which the attacker can send an ASCONF DEL-IP (SCTP AUTH/dynamic address reconfiguration must be enabled, e.g. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The input CVSS of 9.8 (AV:N/AC:L/PR:N/UI:N/C:H/I:H/A:H) substantially overstates real-world risk for this bug. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patch: upgrade to Linux 6.12.109, 6.18.50, or 7.2.4 (or 7.3-rc1 / later mainline), or the equivalent back-ported package from your distribution; the fix drops chunks whose transport was removed in sctp_inq_push() alongside the existing rcvr->dead check, and the peer simply retransmits. … Detailed patch versions, workarounds, and compensating controls in full report. |
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