In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
smb_grant_oplock() has two issues in the oplock publication sequence:
1) opinfo is linked into ci->m_op_list (via opinfo_add) before
add_lease_global_list() is called. If add_lease_global_list()
fails (kmalloc returns NULL), the error path frees the opinfo
via __free_opinfo() while it is still linked in ci->m_op_list.
Concurrent m_op_list readers (opinfo_get_list, or direct iteration
in smb_break_all_levII_oplock) dereference the freed node.
2) opinfo->o_fp is assigned after add_lease_global_list() publishes
the opinfo on the global lease list. A concurrent
find_same_lease_key() can walk the lease list and dereference
opinfo->o_fp->f_ci while o_fp is still NULL.
Fix by restructuring the publication sequence to eliminate post-publish
failure:
- Set opinfo->o_fp before any list publication (fixes NULL deref).
- Preallocate lease_table via alloc_lease_table() before opinfo_add()
so add_lease_global_list() becomes infallible after publication.
- Keep the original m_op_list publication order (opinfo_add before
lease list) so concurrent opens via same_client_has_lease() and
opinfo_get_list() still see the in-flight grant.
- Use opinfo_put() instead of __free_opinfo() on err_out so that
the RCU-deferred free path is used.
This also requires splitting add_lease_global_list() to take a
preallocated lease_table and changing its return type from int to void,
since it can no longer fail.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). 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: 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.
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