{"id":"CVE-2026-11812","title":"UpdateHub: race condition on shared context causes out-of-bounds write and DoS","summary":"The UpdateHub management subsystem (subsys/mgmt/updatehub/updatehub.c) drives every update operation through a single file-scope ctx structure that holds the CoAP block context, payload buffer, status code, socket, and a one-element poll…","severity":"low","cvss":2.5,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L","cvssSource":"cna","cwe":["CWE-362"],"vendor":"zephyrproject","product":"zephyr","affected":["zephyr >= 2.0.0 < 4.3.2","zephyr >= 4.4.0 < 4.4.2"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-08-12T18:51:06.812463Z"},"published":"2026-08-10","updated":"2026-11-04","sourceUpdated":"2026-11-04T04:59:15.164Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-11812","references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/551d3f92b36e9604f039101c4e4f623682d02159","label":"Fix commit"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-vprh-rff6-46xp","label":"GHSA-vprh-rff6-46xp"}],"tags":["cve.org"],"epss":0.00104,"epssPercentile":0.01025,"ingestedAt":"2026-11-05T20:33:06.697Z","slug":"CVE-2026-11812","body":"## Overview\n\nThe UpdateHub management subsystem (subsys/mgmt/updatehub/updatehub.c) drives every update operation through a single file-scope ctx structure that holds the CoAP block context, payload buffer, status code, socket, and a one-element poll-fd array fds[1]. Access to ctx was not serialized, and prepare_fds() wrote ctx.fds[ctx.nfds] and incremented ctx.nfds with no bounds check.\n\nTwo independent paths mutate ctx concurrently: the background autohandler running on the system workqueue, and user-triggered operations reached through the updatehub run shell command, direct API calls, or — since the operations are exposed as syscalls — userspace threads. When a second flow enters prepare_fds() while ctx.nfds is already 1, the write lands one element past the array; by struct layout it overlaps the adjacent ctx.sock/ctx.nfds members. More broadly, the unsynchronized sharing lets two flows interleave connection setup and teardown, double-closing a socket descriptor or scribbling the shared buffers.\n\nThe result is corruption of the update subsystem's internal state and denial of service of the firmware-update path; the out-of-bounds write is contained within the ctx structure and there is no demonstrated path to memory outside it or to code execution. Triggering requires a local actor able to invoke update operations (or, with CONFIG_USERSPACE, an unprivileged userspace thread) and to win a timing race against the background handler; remote peers cannot control the race timing. The fix serializes the entry points with a mutex and adds a bounds check to prepare_fds().\n\n## Affected\n\n- `zephyr >= 2.0.0 < 4.3.2`\n- `zephyr >= 4.4.0 < 4.4.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":14,"depthScoreParts":{"impact":13.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}