ZephyrProject Zephyr up to 4.4.2 Object Transfer Service ots_oacp.c oacp_ind_send uninitialized resource

Summaryinfo

A vulnerability, which was classified as critical, has been found in ZephyrProject Zephyr up to 4.4.2. Affected by this vulnerability is the function oacp_ind_send of the file subsys/bluetooth/services/ots/ots_oacp.c of the component Object Transfer Service. Performing a manipulation results in uninitialized resource. This vulnerability is known as CVE-2026-81038. Remote exploitation of the attack is possible. No exploit is available. Applying a patch is the recommended action to fix this issue.

Detailsinfo

A vulnerability was found in ZephyrProject Zephyr up to 4.4.2. It has been classified as critical. This affects the function oacp_ind_send of the file subsys/bluetooth/services/ots/ots_oacp.c of the component Object Transfer Service. The manipulation with an unknown input leads to a uninitialized resource vulnerability. CWE is classifying the issue as CWE-908. The product uses or accesses a resource that has not been initialized. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

The Object Transfer Service server builds its Object Action Control Point (OACP) response indication in oacp_ind_send() (subsys/bluetooth/services/ots/ots_oacp.c). Before this fix the four-byte Checksum Value field was appended whenever the requested op code was BT_GATT_OTS_OACP_PROC_CHECKSUM_CALC, regardless of the result code. The response payload is a bare, uninitialized four-byte stack buffer declared with NET_BUF_SIMPLE_DEFINE(resp_param, sizeof(uint32_t)) in bt_gatt_ots_oacp_write(), and it is filled only on the success path of oacp_checksum_proc_validate(). On every failure path the buffer is still empty, so net_buf_simple_pull_le32() was invoked on a zero-length buffer. The OACP characteristic and its client characteristic configuration descriptor are declared with BT_GATT_PERM_WRITE and BT_GATT_PERM_READ | BT_GATT_PERM_WRITE, so no pairing, encryption, or authentication is required. Any peer within radio range that can connect to a device running the OTS server can enable OACP indications and write a nine-byte Calculate Checksum command that fails validation — for example by issuing it with no object selected, which returns BT_GATT_OTS_OACP_RES_INV_OBJ. Because oacp_command_decode() accepts the Calculate Checksum op code unconditionally (it is not guarded by CONFIG_BT_OTS_OACP_CHECKSUM_SUPPORT), builds without checksum support are reachable too: they answer BT_GATT_OTS_OACP_RES_OPCODE_NOT_SUP and take the same bad path. On builds with CONFIG_ASSERT enabled, the zero-length pull trips the assertion inside net_buf_simple_pull_mem() and panics the device, giving a remotely triggered denial of service. On builds with assertions disabled there is no check: the pull returns the untouched stack array and four bytes of uninitialized stack memory are copied into the indication and transmitted to the peer, repeatable on every request. The disclosure is bounded to four bytes per request and the write stays inside the seven-byte res indication buffer, so there is no memory corruption; the impact is uninitialized-memory disclosure plus an availability loss in assertion-enabled configurations.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-81038 since 08/26/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available.

Applying the patch 36145a6f1164e2e0a18c8c83d5b1be6e7d3f6e23 is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• ZephyrProject

Name

• Zephyr

Version

• 4.4.0
• 4.4.1
• 4.4.2

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CPE 2.2info

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