CVE-2025-21421

Q: What is the severity of CVE-2025-21421?

CVE-2025-21421 has a CVSS score of 7.8 (HIGH). This vulnerability allows memory corruption when processing escape codes in a Qualcomm API, potentially leading to arbitrary code execution. It affects systems using Qualcomm chipsets with vulnerable firmware. Attackers could exploit this to gain elevated privileges or crash affected devices.

7.8 HIGH

📋 TL;DR

This vulnerability allows memory corruption when processing escape codes in a Qualcomm API, potentially leading to arbitrary code execution. It affects systems using Qualcomm chipsets with vulnerable firmware. Attackers could exploit this to gain elevated privileges or crash affected devices.

💻 Affected Systems

Products:

Qualcomm chipsets with vulnerable firmware

Versions: Specific firmware versions listed in Qualcomm's April 2025 security bulletin

Operating Systems: Android, Linux-based systems using Qualcomm chips

Default Config Vulnerable: ⚠️ Yes

Notes: Affects devices using Qualcomm processors with the vulnerable API implementation. Check Qualcomm's bulletin for specific chipset models.

📦 What is this software?

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, or persistent backdoor installation.

🟠

Likely Case

Local privilege escalation allowing attackers to gain higher privileges on already compromised systems.

🟢

If Mitigated

Denial of service through system crashes if memory corruption cannot be controlled for code execution.

🌐 Internet-Facing: MEDIUM - Requires specific API access but could be exploited remotely if vulnerable services are exposed.

🏢 Internal Only: HIGH - Internal attackers or malware with local access could easily exploit this for privilege escalation.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires understanding of memory corruption techniques and API interaction. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firmware updates specified in Qualcomm's April 2025 security bulletin

Vendor Advisory: https://docs.qualcomm.com/product/publicresources/securitybulletin/april-2025-bulletin.html

Restart Required: Yes

Instructions:

1. Check Qualcomm's security bulletin for affected chipset models. 2. Contact device manufacturer for firmware updates. 3. Apply firmware updates following manufacturer instructions. 4. Reboot device after update completion.

🔧 Temporary Workarounds

Disable vulnerable API if unused

all

If the specific API processing escape codes is not required, disable it to prevent exploitation.

Check device documentation for API disablement procedures

Implement memory protection controls

linux

Enable ASLR and other memory protection mechanisms to make exploitation more difficult.

echo 2 > /proc/sys/kernel/randomize_va_space

🧯 If You Can't Patch

Segment network to isolate vulnerable devices from critical systems
Implement strict access controls and monitoring for devices using Qualcomm chipsets

🔍 How to Verify

Check if Vulnerable:

Check device firmware version against Qualcomm's security bulletin. Use 'getprop ro.build.fingerprint' on Android or check /proc/cpuinfo on Linux systems.

Check Version:

Android: getprop ro.build.fingerprint; Linux: cat /proc/cpuinfo | grep -i qualcomm

Verify Fix Applied:

Verify firmware version has been updated to patched version specified in Qualcomm's bulletin.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
Memory access violation errors
Unexpected process crashes

Network Indicators:

Unusual API calls to Qualcomm-specific services
Traffic patterns indicating memory corruption attempts

SIEM Query:

source="kernel" AND ("panic" OR "segmentation fault") AND process="*qualcomm*"

📊 Metadata

CVE ID: CVE-2025-21421

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-126

EPSS Score: 0.07% exploit probability (20.9th percentile)

Published: April 7, 2025

Last Updated: August 19, 2025

🔗 References

https://docs.qualcomm.com/product/publicresources/securitybulletin/april-2025-bulletin.html Vendor Advisory