In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: oa_tc6: fix tx skb race condition between reference pointers
There are two skb pointers to manage tx skb's enqueued from n/w stack.
waiting_tx_skb pointer points to the tx skb which needs to be processed
and ongoing_tx_skb pointer points to the tx skb which is being processed.
SPI thread prepares the tx data chunks from the tx skb pointed by the
ongoing_tx_skb pointer. When the tx skb pointed by the ongoing_tx_skb is
processed, the tx skb pointed by the waiting_tx_skb is assigned to
ongoing_tx_skb and the waiting_tx_skb pointer is assigned with NULL.
Whenever there is a new tx skb from n/w stack, it will be assigned to
waiting_tx_skb pointer if it is NULL. Enqueuing and processing of a tx skb
handled in two different threads.
Consider a scenario where the SPI thread processed an ongoing_tx_skb and
it moves next tx skb from waiting_tx_skb pointer to ongoing_tx_skb pointer
without doing any NULL check. At this time, if the waiting_tx_skb pointer
is NULL then ongoing_tx_skb pointer is also assigned with NULL. After
that, if a new tx skb is assigned to waiting_tx_skb pointer by the n/w
stack and there is a chance to overwrite the tx skb pointer with NULL in
the SPI thread. Finally one of the tx skb will be left as unhandled,
resulting packet missing and memory leak.
- Consider the below scenario where the TXC reported from the previous
transfer is 10 and ongoing_tx_skb holds an tx ethernet frame which can be
transported in 20 TXCs and waiting_tx_skb is still NULL.
tx_credits = 10; /* 21 are filled in the previous transfer */
ongoing_tx_skb = 20;
waiting_tx_skb = NULL; /* Still NULL */
- So, (tc6->ongoing_tx_skb || tc6->waiting_tx_skb) becomes true.
- After oa_tc6_prepare_spi_tx_buf_for_tx_skbs()
ongoing_tx_skb = 10;
waiting_tx_skb = NULL; /* Still NULL */
- Perform SPI transfer.
- Process SPI rx buffer to get the TXC from footers.
- Now let's assume previously filled 21 TXCs are freed so we are good to
transport the next remaining 10 tx chunks from ongoing_tx_skb.
tx_credits = 21;
ongoing_tx_skb = 10;
waiting_tx_skb = NULL;
- So, (tc6->ongoing_tx_skb || tc6->waiting_tx_skb) becomes true again.
- In the oa_tc6_prepare_spi_tx_buf_for_tx_skbs()
ongoing_tx_skb = NULL;
waiting_tx_skb = NULL;
- Now the below bad case might happen,
Thread1 (oa_tc6_start_xmit) Thread2 (oa_tc6_spi_thread_handler)
--------------------------- -----------------------------------
- if waiting_tx_skb is NULL
- if ongoing_tx_skb is NULL
- ongoing_tx_skb = waiting_tx_skb
- waiting_tx_skb = skb
- waiting_tx_skb = NULL
...
- ongoing_tx_skb = NULL
- if waiting_tx_skb is NULL
- waiting_tx_skb = skb
To overcome the above issue, protect the moving of tx skb reference from
waiting_tx_skb pointer to ongoing_tx_skb pointer and assigning new tx skb
to waiting_tx_skb pointer, so that the other thread can't access the
waiting_tx_skb pointer until the current thread completes moving the tx
skb reference safely.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (4.7): severity, escalated by confirmed exploitation. This CVE's 4.7 is its impact severity (EG Severity), not escalated.
- EG Severity
- 4.7 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-25). 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