In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Reject unhashed UDP sockets on sockmap update
UDP sockets get SOCK_RCU_FREE set when (auto-)bound. This means
sk_is_refcounted(unbound) = true, while sk_is_refcounted(bound) = false.
Because sockmap accepts unbound UDP sockets, a BPF program can increment a
socket's refcount via lookup. If the socket is subsequently bound, the
transition from unbound to bound causes bpf_sk_release() to skip the
decrement of the refcount, causing a memory leak.
unreferenced object 0xffff88810bc2eb40 (size 1984):
comm "test_progs", pid 2451, jiffies 4295320596
hex dump (first 32 bytes):
7f 00 00 01 7f 00 00 01 d2 04 1b b7 04 d2 00 00 ................
02 00 01 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............
backtrace (crc bdee079d):
kmem_cache_alloc_noprof+0x557/0x660
sk_prot_alloc+0x69/0x240
sk_alloc+0x30/0x460
inet_create+0x2ce/0xf80
__sock_create+0x25b/0x5c0
__sys_socket+0x119/0x1d0
__x64_sys_socket+0x72/0xd0
do_syscall_64+0xa1/0x5f0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Instead of special-casing for refcounted sockets, reject unhashed UDP
sockets during sockmap updates, as there is no benefit to supporting those.
This effectively reverts the commit under Fixes, with two exceptions:
- sock_map_sk_state_allowed() maintains a fall-through
return true.
- In the spirit of commit b8b8315e39ff ("bpf, sockmap: Remove unhash
handler for BPF sockmap usage"), the proto::unhash BPF handler is not
reintroduced.
Historical note: this issue is related to commit 67312adc96b5 ("bpf: reject
unhashed sockets in bpf_sk_assign").
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
- EG Severity
- Not assessed: no CVSS publishedA missing CVSS is not a severity of zero.
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-17). 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
- No SSVC decision: EchelonGraph has not assessed this CVECISA 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: the BOD 26-04 block below.
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