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AndroidOperating system · Google

CVE-2023-21077

MEDIUM · 6.7 CVSS v3.1 Published 2023-03-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In rtt_unpack_xtlv_cbfn of dhd_rtt.c, there is a possible out of bounds write due to a buffer overflow. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-257289560References: N/A

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A buffer overflow vulnerability exists in the rtt_unpack_xtlv_cbfn function within dhd_rtt.c in the Android kernel. The function fails to properly validate buffer bounds before writing data, allowing an out-of-bounds write that can be exploited for local privilege escalation. The vulnerability is in the Wi-Fi RTT (Round-Trip-Time) functionality and requires System-level privileges to exploit.

MitigationApply the vendor-provided kernel patch for Android ID A-257289560 which adds proper bounds checking in the rtt_unpack_xtlv_cbfn function to prevent the buffer overflow. Organizations should deploy monthly Android security updates to receive this kernel-level patch.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AndroidOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Android security patch level
    Check Settings > About Phone > Security Patch Level. Compare the date to the patch that contains the fix for A-257289560 (typically the January 2023 or later Android security update)
    Affected if The Security Patch Level is earlier than the patch containing the fix (pre-January 2023 security update)
  2. Confirm Wi-Fi RTT is enabled
    Check if the device has Wi-Fi RTT (IEEE 802.11mc) capability and if Location permissions are granted to apps that might trigger RTT scans. On the device, go to Settings > Location > Wi-Fi scanning and verify if Wi-Fi RTT is actively used or can be triggered.
    Affected if Wi-Fi RTT functionality is present and accessible on the device - this is the attack surface for the vulnerability
  3. Check kernel version for patch presence
    Run 'uname -r' or check /proc/version to get the kernel version. Then verify if the specific patch for A-257289560 has been applied by checking kernel symbols or by examining if the rtt_unpack_xtlv_cbfn function in the loaded Wi-Fi driver module contains the bounds-checking logic.
    Affected if The kernel version is older and lacks the A-257289560 patch, or the vulnerable function lacks proper bounds validation
  4. Identify Wi-Fi driver component
    Check which Wi-Fi driver is in use (typically Broadcom/cywdhd for many Android devices). Look for the dhd_rtt.c module by examining /system/lib/modules or /vendor/lib/modules for wireless driver files.
    Affected if The device uses a Broadcom-based Wi-Fi driver (dhd.ko or similar) that contains the vulnerable rtt_unpack_xtlv_cbfn function

A device is affected if it runs an Android version without the A-257289560 patch (pre-January 2023 security update), has Wi-Fi RTT functionality enabled, and uses a vulnerable Wi-Fi driver containing the unpatched rtt_unpack_xtlv_cbfn function.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-provided kernel patch for Android ID A-257289560 which adds proper bounds checking in the rtt_unpack_xtlv_cbfn function to prevent the buffer overflow. Organizations should deploy monthly Android security updates to receive this kernel-level patch.

Recommended fix High confidence

Android Security Patch Level November 2023 or later (2023-11-01 or 2023-12-01)

  1. 1. Go to Settings > System > System Update on the Android device
  2. 2. Check for and install the latest Android security update
  3. 3. Ensure the installed security patch level is November 2023 or later (the bulletin containing this fix)
  4. 4. Verify the patch was applied by checking Settings > About Phone > Android version > Security patch level
Caveat Standard Android security update - no expected breaking changes for user applications

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,120
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-21077 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data