In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Validate the persistent meta data subbuf array
The meta data for a mapped ring buffer contains an array of indexes of all
the subbuffers. The first entry is the reader page, and the rest of the
entries lay out the order of the subbuffers in how the ring buffer link
list is to be created.
The validator currently makes sure that all the entries are within the
range of 0 and nr_subbufs. But it does not check if there are any
duplicates.
While working on the ring buffer, I corrupted this array, where I added
duplicates. The validator did not catch it and created the ring buffer
link list on top of it. Luckily, the corruption was only that the reader
page was also in the writer path and only presented corrupted data but did
not crash the kernel. But if there were duplicates in the writer side,
then it could corrupt the ring buffer link list and cause a crash.
Create a bitmask array with the size of the number of subbuffers. Then
clear it. When walking through the subbuf array checking to see if the
entries are within the range, test if its bit is already set in the
subbuf_mask. If it is, then there is duplicates and fail the validation.
If not, set the corresponding bit and continue.
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