CVE-2026-33555
MEDIUMDescription
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 22% of all known CVEs.
References
Related Vulnerabilities
Other CWE-130 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-14847 | High | 7.5 | 83% | KEV | Fix |
| CVE-2024-39614 | High | 7.5 | 29% | - | Fix |
| CVE-2021-36090 | High | 7.5 | 13% | - | Fix |
| CVE-2021-35516 | High | 7.5 | 12% | - | Fix |
| CVE-2021-35517 | High | 7.5 | 11% | - | Fix |
| CVE-2019-3862 | High | 7.3 | 8.1% | - | Fix |
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Markdown
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<a href="https://tridentstack.com/cve/CVE-2026-33555"><img src="https://tridentstack.com/cve/badge/CVE-2026-33555.svg" alt="CVE-2026-33555"></a>Find and fix vulnerabilities across your fleet
TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.
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 2026-06-29.