In the Linux kernel, the following vulnerability has been resolved:
media: cec: stm32: prevent out-of-bounds write on RX overflow
stm32_rx_done() appends each received CEC byte to rx_msg.msg[] using
rx_msg.len as the write index, incrementing it on every RXBR
(receive-byte-ready) interrupt without checking it against the buffer
size:
cec->rx_msg.msg[cec->rx_msg.len++] = val & 0xFF;
rx_msg.msg[] is a fixed CEC_MAX_MSG_SIZE (16) byte array in struct
cec_msg, and rx_msg.len is only reset on RXACKE/RXOVR or after a
completed message (RXEND). The number of bytes received before RXEND is
decided by the remote CEC device (it sets EOM), not by the driver. A
peer that keeps sending bytes without ending the message drives RXBR
repeatedly, pushing rx_msg.len past 16 and writing peer-controlled bytes
out of bounds into the surrounding memory. This is reachable in normal
operation once the driver has probed and receiving is enabled, from the
IRQ thread, without any local privilege.
The length check in the CEC core runs on the consumer side, after the
byte has been stored, so it does not prevent the overflow. Bound the
index in the driver before the store, as the other platform CEC drivers
already do (e.g. tegra_cec), dropping the excess bytes of an overlong
frame.
Found by static analysis tool CodeQL.
media: cec: stm32: prevent out-of-bounds write on RX overflow
stm32_rx_done() appends each received CEC byte to rx_msg.msg[] using
rx_msg.len as the write index, incrementing it on every RXBR
(receive-byte-ready) interrupt without checking it against the buffer
size:
cec->rx_msg.msg[cec->rx_msg.len++] = val & 0xFF;
rx_msg.msg[] is a fixed CEC_MAX_MSG_SIZE (16) byte array in struct
cec_msg, and rx_msg.len is only reset on RXACKE/RXOVR or after a
completed message (RXEND). The number of bytes received before RXEND is
decided by the remote CEC device (it sets EOM), not by the driver. A
peer that keeps sending bytes without ending the message drives RXBR
repeatedly, pushing rx_msg.len past 16 and writing peer-controlled bytes
out of bounds into the surrounding memory. This is reachable in normal
operation once the driver has probed and receiving is enabled, from the
IRQ thread, without any local privilege.
The length check in the CEC core runs on the consumer side, after the
byte has been stored, so it does not prevent the overflow. Bound the
index in the driver before the store, as the other platform CEC drivers
already do (e.g. tegra_cec), dropping the excess bytes of an overlong
frame.
Found by static analysis tool CodeQL.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 12 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-787 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 11 Sep 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: media: cec: stm32: prevent out-of-bounds write on RX overflow stm32_rx_done() appends each received CEC byte to rx_msg.msg[] using rx_msg.len as the write index, incrementing it on every RXBR (receive-byte-ready) interrupt without checking it against the buffer size: cec->rx_msg.msg[cec->rx_msg.len++] = val & 0xFF; rx_msg.msg[] is a fixed CEC_MAX_MSG_SIZE (16) byte array in struct cec_msg, and rx_msg.len is only reset on RXACKE/RXOVR or after a completed message (RXEND). The number of bytes received before RXEND is decided by the remote CEC device (it sets EOM), not by the driver. A peer that keeps sending bytes without ending the message drives RXBR repeatedly, pushing rx_msg.len past 16 and writing peer-controlled bytes out of bounds into the surrounding memory. This is reachable in normal operation once the driver has probed and receiving is enabled, from the IRQ thread, without any local privilege. The length check in the CEC core runs on the consumer side, after the byte has been stored, so it does not prevent the overflow. Bound the index in the driver before the store, as the other platform CEC drivers already do (e.g. tegra_cec), dropping the excess bytes of an overlong frame. Found by static analysis tool CodeQL. | |
| Title | media: cec: stm32: prevent out-of-bounds write on RX overflow | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-11T19:46:36.679Z
Reserved: 2026-09-11T19:38:34.759Z
Link: CVE-2026-89725
No data.
Status : Received
Published: 2026-09-11T20:20:02.567
Modified: 2026-09-11T20:20:02.567
Link: CVE-2026-89725
OpenCVE Enrichment
Updated: 2026-09-12T07:00:14Z
Weaknesses