In the Linux kernel, the following vulnerability has been resolved:
bridge: Fix sleep in atomic context in netlink path
Since the introduction of the netlink configuration path for bridge
ports in commit 25c71c75ac87 ("bridge: bridge port parameters over
netlink"), br_setport() was always called with the bridge lock held
around it. Back then this decision made sense: The bridge lock protects
the STP state of the bridge and its ports and at that time the function
only processed three STP related netlink attributes (cost, priority and
state).
Nowadays, br_setport() processes a lot more attributes and most of them
do not need the bridge lock:
* Bridge flags: Only require RTNL. Read locklessly by the data path.
Annotations can be added in net-next.
* FDB port flushing: Only requires the FDB lock.
* Multicast attributes: Only require the multicast lock.
* Group forward mask: Only requires RTNL. Read locklessly by the data
path. Annotations can be added in net-next.
* Backup port and NHID: Only require RTNL. Read locklessly by the data
path.
This is a problem as the bridge calls dev_set_promiscuity() when certain
bridge port flags change and this function can sleep since the commit
cited below, resulting in a splat such as [1].
Fix this by reducing the scope of the bridge lock and only take it when
processing the three STP related attributes that require it. This is
consistent with the multicast attributes where each attribute acquires
the multicast lock instead of having one critical section for all
relevant attributes.
[1]
BUG: sleeping function called from invalid context at net/core/dev_addr_lists.c:1262
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 356, name: bridge
preempt_count: 201, expected: 0
RCU nest depth: 0, expected: 0
2 locks held by bridge/356:
#0: ffffffff919473a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg (net/core/rtnetlink.c:80 net/core/rtnetlink.c:7002)
#1: ffff888115072d58 (&br->lock){+...}-{3:3}, at: br_setlink (./include/linux/spinlock.h:348 net/bridge/br_netlink.c:1117)
Preemption disabled at:
0x0
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
Call Trace:
dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
__might_resched.cold (kernel/sched/core.c:9163)
netif_rx_mode_run (net/core/dev_addr_lists.c:1262)
netif_rx_mode_sync (net/core/dev_addr_lists.c:1428)
dev_set_promiscuity (net/core/dev_api.c:289)
br_manage_promisc (net/bridge/br_if.c:135 net/bridge/br_if.c:172)
br_port_flags_change (net/bridge/br_if.c:242 net/bridge/br_if.c:747)
br_setport (net/bridge/br_netlink.c:1000)
br_setlink (net/bridge/br_netlink.c:1118)
rtnl_bridge_setlink (net/core/rtnetlink.c:5572)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7005)
netlink_rcv_skb (net/netlink/af_netlink.c:2550)
netlink_unicast (net/netlink/af_netlink.c:1318 net/netlink/af_netlink.c:1344)
netlink_sendmsg (net/netlink/af_netlink.c:1894)
__sock_sendmsg (net/socket.c:787 (discriminator 4) net/socket.c:802 (discriminator 4))
____sys_sendmsg (net/socket.c:2698)
___sys_sendmsg (net/socket.c:2752)
__sys_sendmsg (net/socket.c:2784)
do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
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
- 0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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