CVE-2021-46980

CVE-2021-46980 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

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.

Frequently asked questions

What is CVE-2021-46980?
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.
How severe is CVE-2021-46980?
CVE-2021-46980 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2021-46980 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-46980?
CVE-2021-46980 primarily affects Linux Linux Kernel. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-46980?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2021-46980 have an EU (EUVD) identifier?
Yes. CVE-2021-46980 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-33628.
When was CVE-2021-46980 published?
CVE-2021-46980 was published on 2024-02-28 and last updated on 2026-06-17.

References

Affected products (2)

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