CVE-2026-76788 (GCVE-0-2026-76788)
Vulnerability from cvelistv5
Published
2026-10-19 20:39
Modified
2026-10-20 18:08
Severity ?
8.8 (High) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
Summary
The OSDP Control Panel reply parser cp_decode_response() in subsys/mgmt/osdp/src/osdp_cp.c decodes replies from a Peripheral Device into a stack-allocated struct osdp_event. For the REPLY_KEYPPAD and REPLY_RAW reply types, the payload length is taken from the received frame and the only validation performed is that the declared length is self-consistent with the number of payload bytes present in the frame. Because the attacker controls both the length field and the frame length, that check imposes no bound, and the subsequent memcpy() writes into the fixed 64-byte data arrays of struct osdp_event_keypress / struct osdp_event_cardread (OSDP_EVENT_MAX_DATALEN). The sibling REPLY_FMT handler in the same switch already carried the missing > OSDP_EVENT_MAX_DATALEN bound. The defect is reached from cp_process_reply(), which reads bytes from the OSDP RS-485 channel and passes them through osdp_phy_check_packet() and osdp_phy_decode_packet() before dispatching on the reply ID. Triggering it requires CONFIG_OSDP with CONFIG_OSDP_MODE_CP and an application event callback registered (the normal Control Panel integration), plus a frame carrying a correct SOM, a valid CRC-16, and a matching 2-bit sequence number — all of which are computable or observable by anyone on the bus. No check ties the reply ID to the outstanding command, so an oversized REPLY_KEYPPAD or REPLY_RAW is accepted as the answer to a routine CMD_POLL. A malicious or compromised card reader, or anyone with access to the RS-485 wiring, can supply such a frame; CONFIG_OSDP_SC_ENABLED only helps while a secure channel is active, and a single unauthenticated frame carrying a bad MAC causes sc_deactivate(), after which plaintext replies are again accepted. With the default CONFIG_OSDP_UART_BUFFER_LENGTH of 256, roughly 180 bytes of fully attacker-chosen data can be written past the end of the stack-allocated event object, over saved registers and the return address on typical Cortex-M and RISC-V frame layouts (Zephyr does not enable stack canaries by default). The impact ranges from a hard crash of the access-control panel to potential control-flow hijack in the context of the OSDP receive thread. The fix adds an OSDP_EVENT_MAX_DATALEN bound to both handlers, capping each memcpy() at the size of its destination.
References
Impacted products
Vendor Product Version
zephyrproject zephyr Version: 3.3.0   ≤ 4.4.2
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-76788",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-20T18:04:45.622908Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-20T18:08:01.647Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
          "defaultStatus": "unaffected",
          "packageName": "zephyr",
          "product": "zephyr",
          "programFiles": [
            "subsys/mgmt/osdp/src/osdp_cp.c"
          ],
          "programRoutines": [
            {
              "name": "cp_decode_response"
            }
          ],
          "vendor": "zephyrproject",
          "versions": [
            {
              "lessThanOrEqual": "4.4.2",
              "status": "affected",
              "version": "3.3.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The OSDP Control Panel reply parser cp_decode_response() in subsys/mgmt/osdp/src/osdp_cp.c decodes replies from a Peripheral Device into a stack-allocated struct osdp_event. For the REPLY_KEYPPAD and REPLY_RAW reply types, the payload length is taken from the received frame and the only validation performed is that the declared length is self-consistent with the number of payload bytes present in the frame. Because the attacker controls both the length field and the frame length, that check imposes no bound, and the subsequent memcpy() writes into the fixed 64-byte data arrays of struct osdp_event_keypress / struct osdp_event_cardread (OSDP_EVENT_MAX_DATALEN). The sibling REPLY_FMT handler in the same switch already carried the missing \u003e OSDP_EVENT_MAX_DATALEN bound.\n\nThe defect is reached from cp_process_reply(), which reads bytes from the OSDP RS-485 channel and passes them through osdp_phy_check_packet() and osdp_phy_decode_packet() before dispatching on the reply ID. Triggering it requires CONFIG_OSDP with CONFIG_OSDP_MODE_CP and an application event callback registered (the normal Control Panel integration), plus a frame carrying a correct SOM, a valid CRC-16, and a matching 2-bit sequence number \u2014 all of which are computable or observable by anyone on the bus. No check ties the reply ID to the outstanding command, so an oversized REPLY_KEYPPAD or REPLY_RAW is accepted as the answer to a routine CMD_POLL. A malicious or compromised card reader, or anyone with access to the RS-485 wiring, can supply such a frame; CONFIG_OSDP_SC_ENABLED only helps while a secure channel is active, and a single unauthenticated frame carrying a bad MAC causes sc_deactivate(), after which plaintext replies are again accepted.\n\nWith the default CONFIG_OSDP_UART_BUFFER_LENGTH of 256, roughly 180 bytes of fully attacker-chosen data can be written past the end of the stack-allocated event object, over saved registers and the return address on typical Cortex-M and RISC-V frame layouts (Zephyr does not enable stack canaries by default). The impact ranges from a hard crash of the access-control panel to potential control-flow hijack in the context of the OSDP receive thread. The fix adds an OSDP_EVENT_MAX_DATALEN bound to both handlers, capping each memcpy() at the size of its destination."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-787",
              "description": "bounds",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T20:39:22.074Z",
        "orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
        "shortName": "zephyr"
      },
      "references": [
        {
          "name": "Fix commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/zephyrproject-rtos/zephyr/commit/f10d55f47c6970e95d3a7c6ba08e6adec3c79acd"
        },
        {
          "name": "GHSA-fgg7-h8p9-9q3w",
          "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-fgg7-h8p9-9q3w"
        }
      ],
      "title": "Stack out-of-bounds write in the OSDP Control Panel reply parser",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
    "assignerShortName": "zephyr",
    "cveId": "CVE-2026-76788",
    "datePublished": "2026-10-19T20:39:22.074Z",
    "dateReserved": "2026-08-19T17:53:26.698Z",
    "dateUpdated": "2026-10-20T18:08:01.647Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-76788\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-20T18:04:45.622908Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-10-20T18:07:49.192Z\"}}], \"cna\": {\"title\": \"Stack out-of-bounds write in the OSDP Control Panel reply parser\", \"metrics\": [{\"format\": \"CVSS\", \"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 8.8, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\"}}], \"affected\": [{\"vendor\": \"zephyrproject\", \"product\": \"zephyr\", \"versions\": [{\"status\": \"affected\", \"version\": \"3.3.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"4.4.2\"}], \"packageName\": \"zephyr\", \"programFiles\": [\"subsys/mgmt/osdp/src/osdp_cp.c\"], \"collectionURL\": \"https://github.com/zephyrproject-rtos/zephyr\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"cp_decode_response\"}]}], \"references\": [{\"url\": \"https://github.com/zephyrproject-rtos/zephyr/commit/f10d55f47c6970e95d3a7c6ba08e6adec3c79acd\", \"name\": \"Fix commit\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-fgg7-h8p9-9q3w\", \"name\": \"GHSA-fgg7-h8p9-9q3w\"}], \"x_generator\": {\"engine\": \"cvelib 1.8.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"The OSDP Control Panel reply parser cp_decode_response() in subsys/mgmt/osdp/src/osdp_cp.c decodes replies from a Peripheral Device into a stack-allocated struct osdp_event. For the REPLY_KEYPPAD and REPLY_RAW reply types, the payload length is taken from the received frame and the only validation performed is that the declared length is self-consistent with the number of payload bytes present in the frame. Because the attacker controls both the length field and the frame length, that check imposes no bound, and the subsequent memcpy() writes into the fixed 64-byte data arrays of struct osdp_event_keypress / struct osdp_event_cardread (OSDP_EVENT_MAX_DATALEN). The sibling REPLY_FMT handler in the same switch already carried the missing \u003e OSDP_EVENT_MAX_DATALEN bound.\\n\\nThe defect is reached from cp_process_reply(), which reads bytes from the OSDP RS-485 channel and passes them through osdp_phy_check_packet() and osdp_phy_decode_packet() before dispatching on the reply ID. Triggering it requires CONFIG_OSDP with CONFIG_OSDP_MODE_CP and an application event callback registered (the normal Control Panel integration), plus a frame carrying a correct SOM, a valid CRC-16, and a matching 2-bit sequence number \\u2014 all of which are computable or observable by anyone on the bus. No check ties the reply ID to the outstanding command, so an oversized REPLY_KEYPPAD or REPLY_RAW is accepted as the answer to a routine CMD_POLL. A malicious or compromised card reader, or anyone with access to the RS-485 wiring, can supply such a frame; CONFIG_OSDP_SC_ENABLED only helps while a secure channel is active, and a single unauthenticated frame carrying a bad MAC causes sc_deactivate(), after which plaintext replies are again accepted.\\n\\nWith the default CONFIG_OSDP_UART_BUFFER_LENGTH of 256, roughly 180 bytes of fully attacker-chosen data can be written past the end of the stack-allocated event object, over saved registers and the return address on typical Cortex-M and RISC-V frame layouts (Zephyr does not enable stack canaries by default). The impact ranges from a hard crash of the access-control panel to potential control-flow hijack in the context of the OSDP receive thread. The fix adds an OSDP_EVENT_MAX_DATALEN bound to both handlers, capping each memcpy() at the size of its destination.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-787\", \"description\": \"bounds\"}]}], \"providerMetadata\": {\"orgId\": \"e2e69745-5e70-4e92-8431-deb5529a81ad\", \"shortName\": \"zephyr\", \"dateUpdated\": \"2026-10-19T20:39:22.074Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-76788\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-20T18:08:01.647Z\", \"dateReserved\": \"2026-08-19T17:53:26.698Z\", \"assignerOrgId\": \"e2e69745-5e70-4e92-8431-deb5529a81ad\", \"datePublished\": \"2026-10-19T20:39:22.074Z\", \"assignerShortName\": \"zephyr\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.