CVE-2026-76151
MEDIUMDescription
Out-of-bounds read (buffer over-read) in the HTTP Cache-Control response header parsing in the QtNetwork module in Qt Group Qt 6.0.0 through 6.8.8, and 6.9.0 through 6.11.1, allows remote attackers to cause a denial of service (application crash) via an excessively large Cache-Control header value returned by an untrusted or compromised HTTP server to an application using QNetworkAccessManager. Only the client side of the connection is affected and 32-bit builds are not affected; the out-of-bounds access is read-only, with no information disclosure and no code execution.
How to fix
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v4 Vector
Exploitability
Impact
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:N/R:A/V:X/RE:X/U:X
Exploit Intelligence
Moderate risk: more likely to be exploited than 51% of all known CVEs.
References
Related Vulnerabilities
Other CWE-125 (Out-of-bounds Read) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2014-0160 | High | 7.5 | 100% | KEV | Fix |
| CVE-2025-5777 | High | 7.5 | 100% | KEV + Ransom | Fix |
| CVE-2021-4034 | High | 7.8 | 94% | KEV + Ransom | Fix |
| CVE-2020-8794 | Critical | 9.8 | 89% | - | Fix |
| CVE-2023-21769 | High | 7.5 | 89% | - | Fix |
| CVE-2023-49285 | High | 8.6 | 88% | - | Fix |
Common questions
How do I fix CVE-2026-76151?
Upgrade qt6-base on debian unstable to 6.11.2+dfsg-5 or later.
Is CVE-2026-76151 being actively exploited?
Not that we know of. CVE-2026-76151 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.67% is the estimated probability that it will be exploited in the next 30 days. That is higher than 51% of all scored CVEs.
How severe is CVE-2026-76151?
CVE-2026-76151 has a CVSS v4 base score of 4.6, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-76151 affect?
Published advisories record a fix for qt6-base (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-18.