In the Linux kernel, the following vulnerability has been resolved:
tipc: fix an information leak in tipc_topsrv_kern_subscr
Use a 8-byte write to initialize sub.usr_handle in
tipc_topsrv_kern_subscr(), otherwise four bytes remain uninitialized
when issuing setsockopt(..., SOL_TIPC, ...).
This resulted in an infoleak reported by KMSAN when the packet was
received:
=====================================================
BUG: KMSAN: kernel-infoleak in copyout+0xbc/0x100 lib/iov_iter.c:169
instrument_copy_to_user ./include/linux/instrumented.h:121
copyout+0xbc/0x100 lib/iov_iter.c:169
_copy_to_iter+0x5c0/0x20a0 lib/iov_iter.c:527
copy_to_iter ./include/linux/uio.h:176
simple_copy_to_iter+0x64/0xa0 net/core/datagram.c:513
__skb_datagram_iter+0x123/0xdc0 net/core/datagram.c:419
skb_copy_datagram_iter+0x58/0x200 net/core/datagram.c:527
skb_copy_datagram_msg ./include/linux/skbuff.h:3903
packet_recvmsg+0x521/0x1e70 net/packet/af_packet.c:3469
____sys_recvmsg+0x2c4/0x810 net/socket.c:?
___sys_recvmsg+0x217/0x840 net/socket.c:2743
__sys_recvmsg net/socket.c:2773
__do_sys_recvmsg net/socket.c:2783
__se_sys_recvmsg net/socket.c:2780
__x64_sys_recvmsg+0x364/0x540 net/socket.c:2780
do_syscall_x64 arch/x86/entry/common.c:50
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd arch/x86/entry/entry_64.S:120
...
Uninit was stored to memory at:
tipc_sub_subscribe+0x42d/0xb50 net/tipc/subscr.c:156
tipc_conn_rcv_sub+0x246/0x620 net/tipc/topsrv.c:375
tipc_topsrv_kern_subscr+0x2e8/0x400 net/tipc/topsrv.c:579
tipc_group_create+0x4e7/0x7d0 net/tipc/group.c:190
tipc_sk_join+0x2a8/0x770 net/tipc/socket.c:3084
tipc_setsockopt+0xae5/0xe40 net/tipc/socket.c:3201
__sys_setsockopt+0x87f/0xdc0 net/socket.c:2252
__do_sys_setsockopt net/socket.c:2263
__se_sys_setsockopt net/socket.c:2260
__x64_sys_setsockopt+0xe0/0x160 net/socket.c:2260
do_syscall_x64 arch/x86/entry/common.c:50
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd arch/x86/entry/entry_64.S:120
Local variable sub created at:
tipc_topsrv_kern_subscr+0x57/0x400 net/tipc/topsrv.c:562
tipc_group_create+0x4e7/0x7d0 net/tipc/group.c:190
Bytes 84-87 of 88 are uninitialized
Memory access of size 88 starts at ffff88801ed57cd0
Data copied to user address 0000000020000400
...
=====================================================
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS. 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