# CVE-2026-11812: Zephyr UpdateHub management state corruption and denial of service

Source: https://junglewise.ai/threats/cve-2026-11812-zephyr-updatehub-management-state-corruption-and-denial-of  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-10. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-11812 · Severity: low · CVSS 2.5 · Published 2026-08-10

The UpdateHub subsystem in Zephyr RTOS, which manages firmware updates, contains an unsynchronized access flaw that allows local actors to trigger concurrent state corruption. An attacker with permission to initiate update operations can race against the background update handler to corrupt the subsystem's internal state, causing firmware-update operations to fail. The vulnerability is a local denial-of-service issue with no exposure of sensitive data or code execution capability.

Technologies: [Zephyr RTOS](https://junglewise.ai/threats/technologies/rtos). Vendors: [Zephyr](https://junglewise.ai/threats/vendors/zephyr).

## Quick answers

**Is CVE-2026-11812 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-11812 being exploited in the wild.

**How severe is CVE-2026-11812?** Low severity, with a CVSS score of 2.5, published 10 August 2026.

**Which products and versions are affected?** Zephyr RTOS <UNKNOWN>.

**Is there a fix for CVE-2026-11812?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-11812 attacked?** It is attacked with local access.

**Am I affected by CVE-2026-11812?** Check whether you run Zephyr RTOS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a race condition and out-of-bounds write in subsys/mgmt/updatehub/updatehub.c. The UpdateHub management subsystem uses a single file-scope ctx structure to track CoAP block context, payload buffers, status codes, and socket state across multiple code paths. Access to ctx is not serialized, and the prepare_fds() function writes to ctx.fds[ctx.nfds] and increments ctx.nfds without bounds checking. Two independent execution paths mutate ctx concurrently: the background autohandler on the system workqueue and user-triggered operations via shell commands, API calls, or syscalls. When a second flow enters prepare_fds() while ctx.nfds is already 1, the write exceeds the one-element fds[1] array and corrupts adjacent ctx.sock/ctx.nfds members. Attack requires local access to invoke update operations and success depends on winning a timing race against the background handler. The fix adds mutex serialization and bounds checking.

## Affected products

- Zephyr RTOS <UNKNOWN>

## Timeline

- 2026-08-10: disclosed

## Related threats

- [Zephyr Bluetooth HCI USB buffer overflow in controller-to-host path](https://junglewise.ai/threats/cve-2026-79982-the-bluetooth-hci-usb-transport-class-of-the-new-usb-device-stack)
- [Zephyr RTOS PECI driver privilege escalation in peci_transfer()](https://junglewise.ai/threats/cve-2026-19676-the-user-mode-verifier-for-the-peci-transfer-system-call-z-vrfy)
- [Zephyr Bluetooth host ATT buffer use-after-free in signed write path](https://junglewise.ai/threats/cve-2026-19938-the-bluetooth-host-s-att-transmit-path-releases-a-buffer-it-does)
- [Zephyr Bluetooth Mesh Access layer delayable message context leak](https://junglewise.ai/threats/cve-2026-19937-the-bluetooth-mesh-access-layer-delayable-message-machinery-in)
- [Zephyr TCP ISN derivation with all-zero key on entropy failure](https://junglewise.ai/threats/cve-2026-19735-the-rfc-6528-initial-sequence-number-implementation-in-subsys-net)