CVE-2026-8247
An Out-of-bounds Write vulnerability in WatchGuard Fireware OS may allow an unauthenticated attacker on the same local network segment to ex
CVSS
8.8
High
EPSS
0.3%
p19
KEV
—
Exploit Today
6
0-100
Published: Jul 3, 2026 · Last modified: Aug 28, 2026 · CWE-120 · CWE-787
0.2%EPSS · 30 days0.3%
2026-08-042026-08-31
An Out-of-bounds Write vulnerability in WatchGuard Fireware OS may allow an unauthenticated attacker on the same local network segment to execute arbitrary code. This vulnerability affects Fireware OS 11.0 up to and including 11.12.4_Update1, 12.0 up to and including 12.12 and 2025.1 up to and including 2026.2.
CVECVSSEPSSKEVRExploitTitleMod.
CVE-2026-9625——
———A denial-of-service security issue exists within RSLinx® Classic. A crafted CIP packet with an oversized embedded message request can cause the RSLinx® Classic service to crash, requiring a restart of the service to recover.9hCVE-2025-12768——
———A security issue exists within FactoryTalk® Historian Machine Edition. An attacker with low-level authentication could exploit this vulnerability to achieve remote code execution on the affected device.9hCVE-2026-841264.3 MED—
———Incorrect boundary conditions in the Layout: Grid component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.8hCVE-2026-835968.8 HIG—
———A flaw was found in WebKitGTK. Processing malicious web content can cause memory corruption due to improper memory handling.9hCVE-2026-137327.8 HIG—
———A flaw was found in GDB's STABS debug format parser. The
read_member_functions() function in gdb/stabsread.c contains a linked
list removal bug in the code that separates destructor and non-destructor
member functions of C++ classes. The bug causes the destructor entries to
remain in the main function list while the list length counter is
decremented, resulting in an out-of-bounds write when the function list
is copied to its final allocated array. An attacker can craft an ELF
binary with malicious .stab and .stabstr sections that triggers this
out-of-bounds write when a user opens the file in GDB and performs any
symbol-inspection operation such as setting a breakpoint. The inferior
process does not need to be executed. Under controlled conditions, this
was demonstrated to achieve execution of arbitrary commands within the
GDB process.9hCVE-2026-143685.4 MED—
———The LwM2M JSON content formatter's get_string() in subsys/net/lib/lwm2m/lwm2m_rw_json.c copies a parsed JSON string into a caller-supplied buffer and NUL-terminates it. The length guard used if (string_length > buflen), which accepts a string whose length is exactly buflen. After memcpy() fills the whole buffer, buf[string_length] = '\0' then writes one byte past the end of the buffer (CWE-787).
The string value and its length are taken directly from the incoming CoAP payload during a LwM2M WRITE: do_write_op_json() parses the payload obtained from coap_packet_get_payload(), and get_string() is invoked from lwm2m_write_handler() (engine_get_string() in subsys/net/lib/lwm2m/lwm2m_message_handling.c) for a LWM2M_RES_TYPE_STRING resource. The destination buf/buflen is either the resource instance's fixed data buffer (res_inst->data_ptr/max_data_len) or the engine validation buffer (msg->ctx->validate_buf). A LwM2M server (the client's DTLS peer) can therefore write a string resource with a value whose length equals the target buffer size and force a one-byte overflow.
The overflow is a single out-of-bounds write of the constant byte 0x00 immediately past the resource or validation buffer, corrupting the adjacent byte in memory. It is not an information leak and the written value is fixed, so it is not a direct code-execution primitive, but it can corrupt adjacent state (an adjacent resource value, a length/flag field, or a struct field) and cause data corruption or a crash. Triggering the write is deterministic; the resulting impact depends on memory layout.
The fix changes the guard to string_length >= buflen, rejecting the exact-length case and aligning the JSON formatter with the other content formatters (lwm2m_rw_plain_text.c, lwm2m_rw_oma_tlv.c, lwm2m_rw_senml_json.c, lwm2m_rw_cbor.c, lwm2m_rw_senml_cbor.c), which already used the correct boundary check.15h