External risk intelligence

Exynos Modem IMS Stack Out-of-Bounds Access Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-33972

The vulnerability resides in the Exynos modem's IMS (IP Multimedia Subsystem) stack, which is a low-level component within mobile device firmware. While it processes network-based signaling, it is not an internet-facing application, service, or management gateway accessible via standard network protocols, making public internet exposure in common deployments very unlikely.

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in the Exynos modem's IMS stack, affecting how it handles incoming data. This flaw could allow unauthorized access and manipulation of sensitive information within the affected technology. The primary concern at this time is to confirm if our environment is exposed to this specific component.

Unvalidated data access in modem software.
Critical flaw impacting core mobile functionality.
Confirm relevance and exposure of this component.

Attack Path

How an attacker could exploit the issue

An attacker could exploit a vulnerability in the Exynos modem's IMS stack by sending specially crafted data over the network. This could lead to unauthorized access to sensitive information, modification of data, and disruption of services.

Requires network access.
Triggered by improper validation.
Risk of information disclosure and disruption.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in the Exynos modem's IMS stack could allow an attacker to affect system data and service behavior by exploiting an out-of-bounds access flaw when improperly validating data. This exposure could occur when the modem handles specific network signaling, potentially impacting the integrity and availability of related system functions.

System data and service functions at risk.
Exposure via improper input validation.
Potential for data corruption or service disruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Exynos modem's IMS stack requires immediate attention from teams responsible for mobile device firmware and security. The first practical step is to identify all Exynos-powered devices within the organization, assess their network exposure and business criticality, and then pinpoint the accountable owner for remediation planning.

Mobile device and security teams own this issue.
Verify Exynos device presence and network exposure.
Plan coordinated firmware updates or mitigation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the Exynos modem IMS stack?

The Exynos modem IMS stack is a foundational software layer in Samsung mobile chips that handles IP Multimedia Subsystem signaling. It manages how mobile devices connect to services like Voice over LTE (VoLTE) and Wi-Fi calling, processing network data to ensure consistent communication and service delivery.

What does CVE-2026-33972 mean by out-of-bounds access?

This refers to a memory handling flaw classified as CWE-1284, where the software accesses data outside the intended memory buffer. Because the modem fails to validate input properly, it can inadvertently read or write to unauthorized memory areas, potentially leading to system instability or data manipulation.

How is this vulnerability triggered?

An attacker triggers this flaw by sending specifically malformed network packets that the modem's IMS stack fails to validate. It is not triggered by user interaction or typical application usage, but rather by the modem's low-level processing of incoming radio signaling data.

Is this CVE a risk to my internet-facing servers?

No, this vulnerability affects mobile device firmware, not traditional web or infrastructure servers. According to Halo Surface Signal, this component is not an internet-facing service or management gateway, making remote exposure via standard network protocols highly unlikely.

What are the first steps to address CVE-2026-33972?

Start by identifying all mobile devices in your environment that utilize Exynos hardware. Once located, coordinate with your mobile fleet or security teams to track manufacturer-provided firmware updates, as this is the primary mechanism for patching low-level modem vulnerabilities.

References

semiconductor.samsung.com/support/quality-support/product-security-updates/

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.