CVE-2026-24084 Overview
CVE-2026-24084 is a weak configuration vulnerability affecting User Equipment (UE) implementations in cellular network stacks. The flaw stems from the UE failing to verify the consistency of its additional security capabilities against those replayed by the network. This gap in the security-capability negotiation process allows a network-positioned attacker to influence the effective security posture of the connection. Qualcomm disclosed the issue in its August 2026 Security Bulletin and classified it under [CWE-1294: Insecure Security Identifier Mechanism]. The vulnerability is network-reachable, requires no privileges, and no user interaction, with confidentiality as the primary impact.
Critical Impact
An attacker on the radio path can manipulate the security-capability exchange to weaken protections on cellular signaling, exposing confidential data carried over the UE-to-network link.
Affected Products
- Qualcomm cellular modem components implementing UE-side security capability handling
- Devices using affected Qualcomm baseband firmware referenced in the August 2026 Security Bulletin
- Downstream OEM smartphones, IoT modules, and connected devices integrating vulnerable Qualcomm chipsets
Discovery Timeline
- 2026-08-04 - CVE-2026-24084 published to NVD
- 2026-08-06 - Last updated in NVD database
Technical Details for CVE-2026-24084
Vulnerability Analysis
The vulnerability resides in the UE's handling of additional security capabilities during connection establishment or reconfiguration with the cellular network. In a compliant implementation, the UE must compare the security capabilities it originally advertised with those the network replays back. This bidirectional check anchors the negotiated security context to the UE's true capability set and prevents downgrade or substitution by a malicious intermediary.
The affected implementation omits or incorrectly performs this consistency check for additional security capabilities. As a result, an attacker positioned between the UE and the legitimate network can alter the replayed capability set without the UE detecting the tampering. The mismatch never triggers a rejection, and the session proceeds with attacker-influenced parameters.
The issue is tracked under [CWE-1294: Insecure Security Identifier Mechanism], reflecting the failure to bind security-relevant identifiers across protocol steps.
Root Cause
The root cause is missing validation logic in the UE's security-mode command processing path. The code accepts replayed additional security capabilities without cross-referencing them against the capability list transmitted by the UE earlier in the attach or handover procedure.
Attack Vector
Exploitation requires an attacker with radio-layer access, such as a rogue base station, IMSI catcher, or man-in-the-middle relay on the air interface. The attacker intercepts the UE's initial capability advertisement, then replays a modified capability set during the security mode command. Because the UE does not verify consistency, the manipulated capabilities are accepted, and the resulting security context reflects the attacker's chosen configuration rather than the UE's actual capabilities.
No verified proof-of-concept code has been published. Technical details are available in the Qualcomm Security Bulletin August 2026.
Detection Methods for CVE-2026-24084
Indicators of Compromise
- Unexpected cellular re-attach events or repeated security mode command exchanges on a device
- Presence of unknown or unauthorized base stations advertising the same PLMN and TAC as the legitimate carrier
- Anomalous downgrades in negotiated ciphering or integrity algorithms reported by device diagnostic logs
Detection Strategies
- Correlate modem diagnostic traces with expected UE capability lists to spot mismatches between advertised and replayed capabilities
- Monitor for rogue base station indicators using RF survey tools and neighboring-cell consistency checks
- Flag devices whose baseband firmware versions match the vulnerable builds listed in the Qualcomm bulletin
Monitoring Recommendations
- Ingest mobile device management (MDM) telemetry that reports baseband version and patch level, and alert on unpatched builds
- Track cellular attach anomalies from managed fleet devices over time to detect targeted radio-layer attacks
- Include Qualcomm advisory identifiers in vulnerability management workflows to track OEM patch propagation
How to Mitigate CVE-2026-24084
Immediate Actions Required
- Inventory devices using Qualcomm cellular chipsets and identify baseband versions referenced in the August 2026 bulletin
- Apply the OEM firmware updates that incorporate Qualcomm's fix as soon as they are published by device manufacturers
- Restrict use of high-value devices to trusted radio environments until patches are deployed
Patch Information
Qualcomm has released fixes referenced in the Qualcomm Security Bulletin August 2026. The fix must reach end users through OEM firmware updates. Device vendors typically publish security bulletins mapping the Qualcomm advisory to specific model builds. Confirm the applied patch level against the vendor's advisory before considering a device remediated.
Workarounds
- Enforce use of Wi-Fi with strong VPN tunneling for sensitive workloads until baseband patches ship
- Disable legacy 2G or non-standalone modes on managed devices where feasible to reduce exposure to rogue base station attacks
- Use encrypted application-layer channels (TLS, VPN) so that any weakening of cellular-layer protections does not directly expose sensitive data
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
