In the Linux kernel, the following vulnerability has been resolved:
ntfs3: validate split-point offset in indx_insert_into_buffer
indx_insert_into_buffer() computes
used = used1 - to_copy - sp_size;
memmove(de_t, Add2Ptr(sp, sp_size), used - le32_to_cpu(hdr1->de_off));
where sp and sp_size come from hdr_find_split(). hdr_find_split()
walks entries by le16_to_cpu(e->size) without validating that each
step stays within hdr->used or that the size field is at least
sizeof(struct NTFS_DE). index_hdr_check(), the on-load gatekeeper,
only validates header-level fields (used, total, de_off) and does
not walk per-entry sizes.
A crafted NTFS image whose leaf INDEX_HDR reports used == total but
contains one interior NTFS_DE with size = 0xFFF0 therefore passes
validation, descends to indx_insert_into_buffer() through the
ntfs_create() -> indx_insert_entry() path, and makes hdr_find_split()
return an sp whose sp_size (0xFFF0) greatly exceeds the remaining
bytes in the buffer. The u32 subtraction underflows and the memmove
count becomes a near-4-GiB value, producing an out-of-bounds kernel
write that corrupts adjacent allocations and panics the kernel.
Reproduced on 7.0.0-rc7 with UML + KASAN via a crafted image and a
single 'touch' inside the mounted directory; crash site resolves to
fs/ntfs3/index.c at the memmove. Trigger requires only local mount
of an attacker-supplied filesystem image (USB, loopback, or removable
media auto-mount).
Reject the split whenever the chosen sp plus its declared size
already extends past hdr1->used. This is the minimal fix; it
preserves the existing hdr_find_split() contract and relies on the
same out: cleanup path as the pre-existing error returns.
A prior OOB read in the very same indx_insert_into_buffer() memmove
was fixed in commit b8c44949044e ("fs/ntfs3: Fix OOB read in
indx_insert_into_buffer") by tightening hdr_find_e(), but that fix
does not cover the split-point size field path addressed here: sp is
returned by hdr_find_split(), not hdr_find_e(), and the underflow is
driven by sp->size rather than hdr->used exceeding hdr->total.
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
- 0.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-18). 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; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days 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; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (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)3 days if the affected system is publicly exposed; 60 days if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). 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