In the Linux kernel, the following vulnerability has been resolved:
smb/client: fix stale page cache in insert/collapse range
smb3_insert_range() and smb3_collapse_range() use
truncate_pagecache_range() to invalidate the affected page cache.
However, if off or old_eof is not page-aligned, the boundary pages are
only partially zeroed and remain uptodate. As a result, the client may
return stale data after a successful insert/collapse range operation.
For example, with 4K pages:
page 0 page 1 page 2
0------4K 4K------8K 8K------12K
^ ^
off=2K old_eof=10K
Page 1 is removed from the page cache, while the boundary pages are
only partially zeroed. After COPYCHUNK moves the data on the server,
these cached pages may still return stale data.
This can be reproduced on a CIFS mount:
bash -c '
FILE=/mnt/scratch/repro
# Use a 6 KiB file so EOF is not page-aligned.
dd if=/dev/urandom of=/tmp/src bs=1K count=6 status=none
# Expected: a 4 KiB hole followed by the original data.
rm -f /tmp/expected
truncate -s 4K /tmp/expected
cat /tmp/src >> /tmp/expected
cp /tmp/src "$FILE"
# Prime the page cache before moving data on the server.
cat "$FILE" > /dev/null
fallocate --insert-range -o 0 -l 4K "$FILE"
if cmp -s /tmp/expected "$FILE"; then
echo "readback: OK"
else
echo "readback: STALE DATA"
fi
'
Fix this by writing back dirty data and discarding the page cache from
the start of the page containing off to EOF before moving data on the
server.
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.NVD CVSS v3 · CVSS v3.0 or v3.1
- 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