CVE-2026-76151
Description
A flaw was found in the QtNetwork module of the Qt Framework. This out-of-bounds read vulnerability allows a remote attacker to cause a denial of service (application crash). This occurs when an application using QNetworkAccessManager processes an excessively large HTTP Cache-Control header value from an untrusted or compromised server. The vulnerability affects only the client side of the connection and results in read-only access, with no information disclosure or code execution.
Statement
Red Hat has evaluated this vulnerability as having an Important severity because an unauthenticated remote server can trigger an immediate application termination by returning an oversized response header, requiring no local privileges. Client software utilizing the Qt 6 networking stack to retrieve web resources is susceptible to crashes when handling malicious caching directives. Red Hat Enterprise Linux 8 and 9 provide Qt 5, which does not contain the affected code and is therefore not vulnerable. Furthermore, this defect is restricted to read-only memory operations and does not facilitate data leakage or code execution.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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