CVE-2026-10849

Description

The hawkBit device management client in subsys/mgmt/hawkbit accumulates the body of an HTTP response from the update server into a heap buffer in response_json_cb() (subsys/mgmt/hawkbit/hawkbit.c). The buffer is sized to hold the received body bytes but reserves no space for a terminating NUL. When the full response has arrived, the code writes response_data[downloaded_size] = '\0' — and whenever the accumulated body length equals the allocation, that terminator lands one byte past the end of the heap object (a heap-based out-of-bounds write, CWE-122 / CWE-787). The body length and fragmentation are taken directly from the parsed HTTP response (rsp->body_frag_start / rsp->body_frag_len) and are fully controlled by the remote hawkBit server, which chooses its own response length. The precise trigger depends on how the buffer grows, and both forms are remotely reachable. Since v4.0.0 the reallocation is sized to exactly downloaded_size + body_len, so any response body larger than the 1100-byte initial buffer makes the out-of-bounds write deterministic; such response sizes are normal for hawkBit deployment metadata. Before v4.0.0 the buffer grew by doubling and the growth check ((downloaded_size + body_len) > response_buffer_size) is false at equality, so a response body whose length is exactly the current allocation — 1100 bytes with the default initial buffer — skips the reallocation entirely and writes the terminator at response_data[1100] of an 1100-byte object. The HTTP length-mismatch check does not catch this, because the declared and received lengths genuinely agree. Either form is reachable by a malicious, compromised, or man-in-the-middle update server (TLS is optional and, when enabled, does not protect against a hostile server), with no authentication of response content and no client-side length cap protecting the write. The out-of-bounds write is a fixed single NUL byte immediately following the allocation, corrupting adjacent allocator metadata or the next allocation. The practical impact is heap corruption leading to denial of service (fault on a subsequent allocation or free), with the bounded, allocator-dependent possibility of further corruption. The fix sizes the buffer to the body length plus one and copies with memcpy, ensuring the terminator always lands within the allocation.

Overview

State: PUBLISHED
Assigner (CNA): zephyr
CVSS severity: HIGH
CVSS score: 8.2 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Effective score: 8.2 / 10 HIGH source: CNA overview
CWE(s): CWE-122, CWE-787
Reserved: 2026-06-04
Published: 2026-08-03 21:21 UTC
Last updated: 2026-08-03 21:21 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/10xxx/CVE-2026-10849.json
Linked Threat: CVE-2026-10849 — Heap out-of-bounds write in Zephyr hawkBit OTA client when terminating server response body

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-08-03 22:16:47 UTC
NVD last modified: 2026-08-04 20:16:47 UTC
NVD CVSS v3.1: 8.2 / 10 HIGH source: vulnerabilities@zephyrproject.org
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Exploitability subscore: 3.9 / 10
Impact subscore: 4.2 / 10
EPSS score: 0.0027 (probability of exploitation in next 30 days)
EPSS percentile: 18.27% vs all CVEs — higher = more likely to be exploited, as of 2026-08-04

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-52447
Assigner: zephyr
Published: Aug 3, 2026, 9:21:32 PM
Updated: Aug 3, 2026, 9:21:32 PM
EUVD base score (CVSS 3.1): 8.2 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
EUVD-reported EPSS: 0.0000
Vendors: zephyrproject
Products: Zephyr (2.4.0 <4.5.0)

ENISA description: The hawkBit device management client in subsys/mgmt/hawkbit accumulates the body of an HTTP response from the update server into a heap buffer in response_json_cb() (subsys/mgmt/hawkbit/hawkbit.c). The buffer is sized to hold the received body bytes but reserves no space for a terminating NUL. When the full response has arrived, the code writes response_data[downloaded_size] = '\0' — and whenever the accumulated body length equals the allocation, that terminator lands one byte past the end of the heap object (a heap-based out-of-bounds write, CWE-122 / CWE-787). The body length and fragmentation are taken directly from the parsed HTTP response (rsp->body_frag_start / rsp->body_frag_len) and are fully controlled by the remote hawkBit server, which chooses its own response length. The precise trigger depends on how the buffer grows, and both forms are remotely reachable. Since v4.0.0 the reallocation is sized to exactly downloaded_size + body_len, so any response body larger than the 1100-byte initial buffer makes the out-of-bounds write deterministic; such response sizes are normal for hawkBit deployment metadata. Before v4.0.0 the buffer grew by doubling and the growth check ((downloaded_size + body_len) > response_buffer_size) is false at equality, so a response body whose length is exactly the current allocation — 1100 bytes with the default initial buffer — skips the reallocation entirely and writes the terminator at response_data[1100] of an 1100-byte object. The HTTP length-mismatch check does not catch this, because the declared and received lengths genuinely agree. Either form is reachable by a malicious, compromised, or man-in-the-middle update server (TLS is optional and, when enabled, does not protect against a hostile server), with no authentication of response content and no client-side length cap protecting the write. The out-of-bounds write is a fixed single NUL byte immediately following the allocation, corrupting adjacent allocator metadata or the next allocation. The practical impact is heap corruption leading to denial of service (fault on a subsequent allocation or free), with the bounded, allocator-dependent possibility of further corruption. The fix sizes the buffer to the body length plus one and copies with memcpy, ensuring the terminator always lands within the allocation.

EUVD references (2)

Affected products (1)

Vendor	Product	Versions	Platforms
zephyrproject	zephyr	`2.4.0` (affected)	—

Vendor references (2)

References embedded in the original CVE record by the assigning CNA.

Fix commit patch
GHSA-39h3-7phx-pwhv

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (2)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/zephyrproject-rtos/zephyr/commit/59d7ab58d853489e6134081cadb11733730264ac vulnerabilities@zephyrproject.org
https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-39h3-7phx-pwhv vulnerabilities@zephyrproject.org

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

CVE-2026-10849 - Exploits & Severity - Feedly

web:feedly.com

Mitigation Update the hawkBit OTA client to a patched version when available. Implement network-level controls to restrict update server connections to trusted, authenticated sources. Enforce HTTPS with certificate pinning for update communications to prevent man-in-the-middle attacks.

2026-08-04 20:27 UTC
Nvd - Cve-2026-20849

web:nvd.nist.gov

Description Reliance on untrusted inputs in a security decision in Windows Kerberos allows an authorized attacker to elevate privileges over a network.

2026-08-04 20:27 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-08-04 20:27 UTC
Addressing Exchange Server May 2026 vulnerability CVE-2026-42897 ...

web:techcommunity.microsoft.com

Hi team, Our organization has successfully implemented the recommended mitigation for CVE - 2026 -42897. However, we are currently experiencing the documented known issues within our environment. Could the Exchange team kindly provide a tentative timeline or ETA for a permanent security update that resolves the underlying vulnerability while addressing these known issues? We would greatly ...

2026-08-04 20:27 UTC
National Vulnerability Database | NIST

web:www.nist.gov

NIST maintains the National Vulnerability Database (NVD), a repository of information on software and hardware flaws that can compromise computer security. This is a key piece of the nation's cybersecurity infrastructure.

2026-08-04 20:27 UTC
Oracle Critical Security Patch Update Advisory - June 2026

web:www.oracle.com

Additional CVEs addressed are: The patch for CVE - 2026 -34481 also addresses CVE - 2026 -34477, CVE - 2026 -34478, CVE - 2026 -34479, and CVE - 2026 -34480. Oracle Fusion Middleware Risk Matrix This Critical Security Patch Update contains 106 new security patches for Oracle Fusion Middleware. 53 of these vulnerabilities may be remotely exploitable without authentication, i.e., may be exploited over a ...

2026-08-04 20:27 UTC
Patch Tuesday - June 2026 - Rapid7

web:www.rapid7.com

Microsoft is publishing 200 vulnerabilities on June 2026 Patch Tuesday, including an HTTP/2 denial of service vulnerability and an elevation of privilege vulnerability in PowerToys.

2026-08-04 20:27 UTC
July 2026 Patch Tuesday: Largest Patch Tuesday 569 CVEs - Tenable

web:www.tenable.com

Microsoft patched 569 CVEs in July 2026 , the largest Patch Tuesday release in its history. 56 critical CVEs patched including three zero-day vulnerabilities.

2026-08-04 20:27 UTC
CVE-2026-10849 | Tenable®

web:www.tenable.com

The practical impact is heap corruption leading to denial of service (fault on a subsequent allocation or free), with the bounded, allocator-dependent possibility of further corruption. The fix sizes the buffer to the body length plus one and copies with memcpy, ensuring the terminator always lands within the allocation.

2026-08-04 20:27 UTC
Patch Tuesday July 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's July 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-08-04 20:27 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-10849.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
          "defaultStatus": "unaffected",
          "packageName": "zephyr",
          "product": "zephyr",
          "programFiles": [
            "subsys/mgmt/hawkbit/hawkbit.c"
          ],
          "vendor": "zephyrproject",
          "versions": [
            {
              "lessThan": "4.5.0",
              "status": "affected",
              "version": "2.4.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The hawkBit device management client in subsys/mgmt/hawkbit accumulates the body of an HTTP response from the update server into a heap buffer in response_json_cb() (subsys/mgmt/hawkbit/hawkbit.c). The buffer is sized to hold the received body bytes but reserves no space for a terminating NUL. When the full response has arrived, the code writes response_data[downloaded_size] = '\\0' \u2014 and whenever the accumulated body length equals the allocation, that terminator lands one byte past the end of the heap object (a heap-based out-of-bounds write, CWE-122 / CWE-787).\n\nThe body length and fragmentation are taken directly from the parsed HTTP response (rsp->body_frag_start / rsp->body_frag_len) and are fully controlled by the remote hawkBit server, which chooses its own response length. The precise trigger depends on how the buffer grows, and both forms are remotely reachable. Since v4.0.0 the reallocation is sized to exactly downloaded_size + body_len, so any response body larger than the 1100-byte initial buffer makes the out-of-bounds write deterministic; such response sizes are normal for hawkBit deployment metadata. Before v4.0.0 the buffer grew by doubling and the growth check ((downloaded_size + body_len) > response_buffer_size) is false at equality, so a response body whose length is exactly the current allocation \u2014 1100 bytes with the default initial buffer \u2014 skips the reallocation entirely and writes the terminator at response_data[1100] of an 1100-byte object. The HTTP length-mismatch check does not catch this, because the declared and received lengths genuinely agree. Either form is reachable by a malicious, compromised, or man-in-the-middle update server (TLS is optional and, when enabled, does not protect against a hostile server), with no authentication of response content and no client-side length cap protecting the write.\n\nThe out-of-bounds write is a fixed single NUL byte immediately following the allocation, corrupting adjacent allocator metadata or the next allocation. The practical impact is heap corruption leading to denial of service (fault on a subsequent allocation or free), with the bounded, allocator-dependent possibility of further corruption. The fix sizes the buffer to the body length plus one and copies with memcpy, ensuring the terminator always lands within the allocation."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-122",
              "description": "bounds",
              "lang": "en",
              "type": "CWE"
            },
            {
              "cweId": "CWE-787",
              "description": "bounds",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-03T21:21:32.890Z",
        "orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
        "shortName": "zephyr"
      },
      "references": [
        {
          "name": "Fix commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/zephyrproject-rtos/zephyr/commit/59d7ab58d853489e6134081cadb11733730264ac"
        },
        {
          "name": "GHSA-39h3-7phx-pwhv",
          "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-39h3-7phx-pwhv"
        }
      ],
      "title": "Heap out-of-bounds write in Zephyr hawkBit OTA client when terminating server response body",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
    "assignerShortName": "zephyr",
    "cveId": "CVE-2026-10849",
    "datePublished": "2026-08-03T21:21:32.890Z",
    "dateReserved": "2026-06-04T12:16:36.322Z",
    "dateUpdated": "2026-08-03T21:21:32.890Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}