CVE-2026-13326 in Qt
Summary
by MITRE • 09/11/2026
An out-of-bounds read in Qt NFC's language code length parsing allows a physically proximate attacker to cause a denial of service or limited memory disclosure via a crafted NFC tag.
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Analysis
by VulDB Data Team • 09/11/2026
The vulnerability identified as an out-of-bounds read within the Qt Near Field Communication (NFC) module specifically targets the logic responsible for parsing language codes embedded in NDEF records on NFC tags. This flaw arises from insufficient validation of length fields associated with these language identifiers, allowing a malicious actor to craft an NFC tag that contains malformed or excessively large length values. When a device running affected Qt software attempts to read such a tag, the parser fails to correctly bound-check the requested data size against the actual available buffer space. This discrepancy triggers a memory access violation where the application reads beyond the allocated boundaries of its internal buffers. The root cause is classified under CWE-125, which denotes an out-of-bounds read vulnerability, indicating that the software does not properly verify whether resource accesses are within the correct limits before utilizing them in operations such as reading or copying data from memory.
From a technical perspective, this flaw exploits the trust placed in NFC tag contents by the host application's parsing routines. In standard NDEF message processing, language codes follow specific formatting rules defined by industry standards to ensure interoperability between devices and tags. However, when an attacker crafts a tag with a length field that exceeds the actual payload size or manipulates it to point to invalid memory regions, the Qt NFC implementation proceeds to read from those unallocated or protected memory areas without raising appropriate exceptions or halting execution safely. This behavior is particularly dangerous because NFC interactions are often handled in background services or system-level daemons that may have elevated privileges relative to user-space applications. The lack of strict boundary checks during the parsing phase allows for predictable exploitation patterns where specific memory addresses can be targeted based on known heap layouts or stack structures within the Qt framework's execution context.
The operational impact of this vulnerability is primarily centered around denial of service and potential information disclosure. A physically proximate attacker, who must be close enough to interact with the target device via NFC, can trigger a crash in the application handling the tag read operation. This results in a denial of service condition where the affected application or system component becomes unresponsive until restarted, disrupting normal operations for end-users relying on NFC functionality such as mobile payments, access control, or data exchange. Furthermore, depending on the specific memory layout and operating system protections, the out-of-bounds read may leak sensitive information stored in adjacent memory locations. This could include partial contents of other variables, pointers, or even cryptographic keys if they reside near the vulnerable buffer, leading to limited but potentially significant memory disclosure. Such disclosures can facilitate further attacks by providing attackers with insights into the application's internal state or bypassing certain security controls that rely on unpredictable memory states.
In terms of threat modeling and attack classification, this vulnerability aligns with ATT&CK technique T1563, which covers Remote Service Session Hijacking through physical proximity interactions when combined with other exploitation vectors, though more directly it falls under the broader category of local privilege escalation or service disruption via crafted inputs. The requirement for physical proximity places this in a specific threat landscape where attackers might target public kiosks, transit systems, or personal devices left unattended. Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Developers should update to versions of Qt that include fixes for the NFC module's parsing logic, ensuring that all length fields are rigorously validated against buffer capacities before any read operations occur. Additionally, implementing strict input validation frameworks within custom applications using Qt NFC can provide an additional layer of defense. Security teams should also consider deploying runtime application self-protection mechanisms or memory corruption mitigations such as Address Space Layout Randomization and stack canaries to reduce the exploitability of out-of-bounds reads even if they cannot be immediately patched in legacy systems. Regular security audits focusing on NDEF parsing routines are recommended to identify similar weaknesses across other NFC-related libraries used within the organization's software ecosystem.