⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● Medium · CVSS 4.8

How to Fix CVE-2026-41281: Information Disclosure in あんしんフィルター for au

Other vulnerabilities in the same area that are worth patching alongside this one:

*By Sai Kiran Pandrala*

⚡ At a glance
SeverityCVSS 4.8 - Medium
Actively exploited?Not currently listed in CISA KEV
Affectedprior to 4.9_b0003
Fixed inSee vendor advisory
Type (CWE)CWE-319: Cleartext transmission of sensitive information

What is CVE-2026-41281?

CVE-2026-41281 is an information disclosure flaw in あんしんフィルター for au. The product returns sensitive data to a caller who should not have access, including credentials, session tokens, or configuration. Disclosure often feeds a follow-up attack chain. Vendor description: Android App "あんしんフィルター for au" provided by KDDI CORPORATION contains Cleartext Transmission of Sensitive Information (CWE-319) vulnerability. A man-in-the-middle attacker may access and modify communications transmitted in plaintext, potentially resulting in information disclosure or data tampering.

Why this CVE matters

Information disclosure flaws are dangerous because they make the next attack easier. Sensitive configuration, session material, or credentials leaked from one endpoint frequently power the follow-on attack that actually takes over the system.

For deployments of あんしんフィルター for au that have been exposed to the public internet during the disclosure window, the operating assumption should be that scanning has already happened. Even where exploitation has not been publicly observed, scanning for the vulnerable fingerprint is cheap and routine. Patching closes the door; log review and credential rotation close out the rest of the response.

Am I affected?

You are affected if your installation matches any of these version ranges:

Check your installed version against the list above. If you cannot determine the version, treat the system as affected and follow the upgrade path below.

Open あんしんフィルター for au's About dialog or run the vendor-documented version-check command. Compare the result against the affected ranges in the advisory.

How to fix CVE-2026-41281

  1. Read the vendor advisory in full: https://jvn.jp/en/jp/JVN24167657/
  2. Upgrade あんしんフィルター for au to the patched build listed in the vendor advisory.
  3. Back up the configuration (and database, where applicable) before upgrading.
  4. Apply the patch in a maintenance window. For HA pairs, upgrade the standby node first, fail over, then upgrade the former primary.
  5. Restart the affected service so the patched binary loads, then verify the new version (see verification section).

# Confirm managed Android devices have the patch (Intune via Microsoft Graph).
Connect-MgGraph -Scopes Device.Read.All
Get-MgDeviceManagementManagedDevice -Filter "operatingSystem eq 'Android'" |
  Select-Object DeviceName, OSVersion, AndroidSecurityPatchLevel

Apply the Android security bulletin update


# CVE-2026-41281 affects Android prior to 4.9_b0003. Fixed in 4.9_b0003.
# Vendor advisory: https://jvn.jp/en/jp/JVN24167657/

# 1. Confirm the device's current security patch level.
adb shell getprop ro.build.version.security_patch

# 2. The patch level must be on or after the date listed in the advisory.
#    If older, install the OTA from Settings -> System -> System update,
#    or sideload the factory image:
adb reboot bootloader
fastboot flash bootloader bootloader-<device>-<build>.img
fastboot reboot bootloader
fastboot -w update image-<device>-<build>.zip


# Confirm managed Android devices have the patch (Intune via Microsoft Graph).
Connect-MgGraph -Scopes Device.Read.All
Get-MgDeviceManagementManagedDevice -Filter "operatingSystem eq 'Android'" |
  Select-Object DeviceName, OSVersion, AndroidSecurityPatchLevel

Verify the fix landed


# CVE-2026-41281 verification checklist.

# 1. Confirm the running version matches 4.9_b0003 (replace the version probe with
#    the platform-specific command shown above).

# 2. Re-scan the host with your vulnerability scanner (Nessus, Qualys, Tenable,
#    OpenVAS, Wazuh). The scanner must no longer flag CVE-2026-41281.

# 3. Inspect recent service and kernel logs for crash-loops or rollback events.
journalctl -u <service-name> --since "10 minutes ago"
dmesg --since "10 minutes ago"

# 4. Cross-check the running build against the vendor advisory:
#    https://jvn.jp/en/jp/JVN24167657/

If you cannot patch immediately

No official workaround exists beyond restricting network exposure to the affected component. Apply the vendor patch as the primary remediation.

How to verify the fix worked

If your installation was internet-reachable during the disclosure window, treat log review as part of the remediation rather than an optional follow-up. Look for unusually long URI paths containing traversal sequences, unexpectedly large responses from the affected endpoint, and outbound requests from the application to internal addresses or cloud-metadata endpoints. Treat any sensitive file the bug could disclose as exposed.

Frequently asked questions

Is CVE-2026-41281 being exploited in the wild?

Public exploitation has not been confirmed by CISA at the time of writing. Treat the patch as time-sensitive anyway; reports often lag actual abuse.

Will a WAF or IDS rule fully mitigate CVE-2026-41281?

No. Network-layer filters can reduce noise and slow opportunistic scanners, but they will not stop a determined attacker. The vendor patch is the only durable fix.

How long should I plan for the upgrade?

Typical vendor-documented upgrade windows for あんしんフィルター for au run from a few minutes to under an hour depending on cluster size. Test in a staging environment first and follow the vendor's documented HA upgrade order.

References

*This guide was assembled from the official vendor advisory, the NVD record, and the CISA KEV catalog entry on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*