In the Linux kernel, the following vulnerability has been resolved:
mptcp: do not queue data on closed subflows
Dipanjan reported a syzbot splat at close time:
WARNING: CPU: 1 PID: 10818 at net/ipv4/af_inet.c:153
inet_sock_destruct+0x6d0/0x8e0 net/ipv4/af_inet.c:153
Modules linked in: uio_ivshmem(OE) uio(E)
CPU: 1 PID: 10818 Comm: kworker/1:16 Tainted: G OE
5.19.0-rc6-g2eae0556bb9d #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Workqueue: events mptcp_worker
RIP: 0010:inet_sock_destruct+0x6d0/0x8e0 net/ipv4/af_inet.c:153
Code: 21 02 00 00 41 8b 9c 24 28 02 00 00 e9 07 ff ff ff e8 34 4d 91
f9 89 ee 4c 89 e7 e8 4a 47 60 ff e9 a6 fc ff ff e8 20 4d 91 f9 <0f> 0b
e9 84 fe ff ff e8 14 4d 91 f9 0f 0b e9 d4 fd ff ff e8 08 4d
RSP: 0018:ffffc9001b35fa78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00000000002879d0 RCX: ffff8881326f3b00
RDX: 0000000000000000 RSI: ffff8881326f3b00 RDI: 0000000000000002
RBP: ffff888179662674 R08: ffffffff87e983a0 R09: 0000000000000000
R10: 0000000000000005 R11: 00000000000004ea R12: ffff888179662400
R13: ffff888179662428 R14: 0000000000000001 R15: ffff88817e38e258
FS: 0000000000000000(0000) GS:ffff8881f5f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020007bc0 CR3: 0000000179592000 CR4: 0000000000150ee0
Call Trace:
__sk_destruct+0x4f/0x8e0 net/core/sock.c:2067
sk_destruct+0xbd/0xe0 net/core/sock.c:2112
__sk_free+0xef/0x3d0 net/core/sock.c:2123
sk_free+0x78/0xa0 net/core/sock.c:2134
sock_put include/net/sock.h:1927 [inline]
__mptcp_close_ssk+0x50f/0x780 net/mptcp/protocol.c:2351
__mptcp_destroy_sock+0x332/0x760 net/mptcp/protocol.c:2828
mptcp_worker+0x5d2/0xc90 net/mptcp/protocol.c:2586
process_one_work+0x9cc/0x1650 kernel/workqueue.c:2289
worker_thread+0x623/0x1070 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
The root cause of the problem is that an mptcp-level (re)transmit can
race with mptcp_close() and the packet scheduler checks the subflow
state before acquiring the socket lock: we can try to (re)transmit on
an already closed ssk.
Fix the issue checking again the subflow socket status under the
subflow socket lock protection. Additionally add the missing check
for the fallback-to-tcp case.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
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.
The score's inputs: 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