In the Linux kernel, the following vulnerability has been resolved:
sctp: stop processing a packet once its association is deleted
sctp_endpoint_bh_rcv() looks the association up only when chunk->asoc is
NULL, and caches the result in chunk->asoc and chunk->transport without
taking a reference.
A packet that matches no association is handed to the endpoint, so a peer
can bundle COOKIE ECHO, SHUTDOWN and SHUTDOWN ACK in one packet. The
COOKIE ECHO creates the association, the SHUTDOWN chunk caches it, and
with the outqueue empty the SHUTDOWN ACK reaches sctp_sf_do_9_2_final(),
so the association and its transports are freed.
The endpoint loop has no counterpart to the asoc->base.dead check in
sctp_assoc_bh_rcv(). The next chunk writes to last_time_heard in the freed
transport and is then passed to sctp_do_sm() with the freed association.
The transport is freed through RCU, so this needs the packet to come off
the socket backlog, where the loop runs in task context.
The endpoint loop cannot do the same check: it holds no reference on the
association, so reading asoc->base.dead would itself be a use-after-free.
Mark the packet for discard in the command interpreter, just before it
deletes the association. That is also before sctp_inq_free() releases the
chunk on the association receive path.
sctp_sf_do_5_2_4_dupcook() issues SCTP_CMD_DELETE_TCB for the temporary
association, while the one the packet belongs to stays alive. A restarting
peer can bundle DATA behind its COOKIE ECHO, so compare against
chunk->asoc and leave that case alone.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it