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CVE Record

CVE-2021-47065: rtw88: Fix array overrun in rtw_get_tx_power_params()

In the Linux kernel, the following vulnerability has been resolved: rtw88: Fix array overrun in rtw_get_tx_power_params() Using a kernel with the Undefined Behaviour Sanity Checker (UBSAN) enabled, the following array overrun is logged: ================================================================================ UBSAN: array-index-out-of-bounds in /home/finger/wireless-drivers-next/drivers/net/wireless/realtek/rtw88/phy.c:1789:34 index 5 is out of range for type 'u8 [5]' CPU: 2 PID: 84 Comm: kworker/u16:3 Tainted: G O 5.12.0-rc5-00086-gd88bba47038e-dirty #651 Hardware name: TOSHIBA TECRA A50-A/TECRA A50-A, BIOS Version 4.50 09/29/2014 Workqueue: phy0 ieee80211_scan_work [mac80211] Call Trace: dump_stack+0x64/0x7c ubsan_epilogue+0x5/0x40 __ubsan_handle_out_of_bounds.cold+0x43/0x48 rtw_get_tx_power_params+0x83a/drivers/net/wireless/realtek/rtw88/0xad0 [rtw_core] ? rtw_pci_read16+0x20/0x20 [rtw_pci] ? check_hw_ready+0x50/0x90 [rtw_core] rtw_phy_get_tx_power_index+0x4d/0xd0 [rtw_core] rtw_phy_set_tx_power_level+0xee/0x1b0 [rtw_core] rtw_set_channel+0xab/0x110 [rtw_core] rtw_ops_config+0x87/0xc0 [rtw_core] ieee80211_hw_config+0x9d/0x130 [mac80211] ieee80211_scan_state_set_channel+0x81/0x170 [mac80211] ieee80211_scan_work+0x19f/0x2a0 [mac80211] process_one_work+0x1dd/0x3a0 worker_thread+0x49/0x330 ? rescuer_thread+0x3a0/0x3a0 kthread+0x134/0x150 ? kthread_create_worker_on_cpu+0x70/0x70 ret_from_fork+0x22/0x30 ================================================================================ The statement where an array is being overrun is shown in the following snippet: if (rate <= DESC_RATE11M) tx_power = pwr_idx_2g->cck_base[group]; else ====> tx_power = pwr_idx_2g->bw40_base[group]; The associated arrays are defined in main.h as follows: struct rtw_2g_txpwr_idx { u8 cck_base[6]; u8 bw40_base[5]; struct rtw_2g_1s_pwr_idx_diff ht_1s_diff; struct rtw_2g_ns_pwr_idx_diff ht_2s_diff; struct rtw_2g_ns_pwr_idx_diff ht_3s_diff; struct rtw_2g_ns_pwr_idx_diff ht_4s_diff; }; The problem arises because the value of group is 5 for channel 14. The trivial increase in the dimension of bw40_base fails as this struct must match the layout of efuse. The fix is to add the rate as an argument to rtw_get_channel_group() and set the group for channel 14 to 4 if rate <= DESC_RATE11M. This patch fixes commit fa6dfe6bff24 ("rtw88: resolve order of tx power setting routines")

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47065 is a Linux kernel bug in the Realtek rtw88 Wi-Fi driver. Under certain channel and rate handling, the driver can read past a small power-index array. The sources show a kernel fix, but do not provide CVSS, impact severity, or evidence of real-world exploitation.

Executive priority

Treat this as a targeted kernel maintenance issue, not an emergency, unless your fleet heavily depends on affected Realtek Wi-Fi devices. The priority is timely kernel patch validation through normal endpoint update processes because public severity and exploitation evidence are incomplete.

Technical view

rtw_get_tx_power_params() can index bw40_base[5] when group becomes 5 for channel 14, while the array has five entries. The fix changes rtw_get_channel_group() behavior using the rate argument so channel 14 maps safely for the relevant rates without changing efuse layout.

Likely exposure

Exposure is limited to Linux systems running affected kernel versions with Realtek rtw88 wireless support. Systems without this driver or hardware are unlikely to be exposed. Distribution kernels may already contain an equivalent backport, so version alone is not enough to decide exposure.

Exploitation context

The bundle reports no KEV listing and no cited evidence of active exploitation. The issue was observed through UBSAN during mac80211 scan work. The sources do not establish practical exploitability, attacker requirements, denial-of-service impact, or privilege impact.

Researcher notes

The key constraint is efuse structure layout: simply enlarging bw40_base was rejected. The fix adjusts channel group selection based on rate. Impact analysis remains limited in the supplied sources; avoid claiming memory corruption exploitability beyond the documented array overrun.

Mitigation direction

  • Apply Linux vendor kernel updates that include the cited rtw88 fix or equivalent backport.
  • Check distribution advisories for CVE-2021-47065 before assuming upstream version status.
  • Prioritize laptops or endpoints using Realtek rtw88 Wi-Fi hardware.
  • If updates are unavailable, follow vendor guidance for temporary driver or hardware risk reduction.

Validation and detection

  • Inventory Linux systems using Realtek rtw88 wireless drivers or hardware.
  • Confirm the running kernel includes one of the cited stable commits or an equivalent backport.
  • Review vulnerability scanner results against distribution-specific kernel package metadata.
  • Check kernel logs for related UBSAN array-index-out-of-bounds reports if UBSAN is enabled.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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ADP provider summaries

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other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxfa6dfe6bff246ddd5be3cfe81637f137acd6c294, fa6dfe6bff246ddd5be3cfe81637f137acd6c294, fa6dfe6bff246ddd5be3cfe81637f137acd6c294, fa6dfe6bff246ddd5be3cfe81637f137acd6c294, fa6dfe6bff246ddd5be3cfe81637f137acd6c294unaffected
LinuxLinux5.3, 0, 5.4.119, 5.10.37, 5.11.21, 5.12.4, 5.13affected
Weakness

CWE details

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