CVE•Published 2026-04-13•0 articles on news•6 live references•NVD data
CVE-2026-33555
Vulnerability data via NVD (ingested)
CVSS v3.1
4.0
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
EPSS percentile
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Weaknesses (CWE)
Description
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.
Timeline
Published 2026-04-13
Modified 2026-04-13
External references
Search for exposed instances
Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).
More intel sources (5)
Shodan report
vuln:CVE-2026-33555Country / ASN / product breakdown for the vuln query.
Censys
vulnerabilities.cve_id: CVE-2026-33555Censys host search filtered to this CVE id.
grep.app
CVE-2026-33555Public source-code mentions — fast PoC discovery.
GitHub code
CVE-2026-33555GitHub code search for direct mentions.
Google dork
"CVE-2026-33555" exploit -site:nvd.nist.govWrite-ups and news, NVD excluded.
Known PoCs on GitHub (4)
CVE-2026-335554 repos
DarkFunct/TK-CVE-RepoPython
TK-CVE-Repo
holmanholdings/lionguardPython
Cathedral-Grade Security for AI Agents. Attack vectors updated daily. Local-first, zero API cost. MIT licensed.
r3verii/CVE-2026-33555Python
One zero-byte QUIC packet is enough to desynchronize HAProxy's backend connection pool and smuggle HTTP requests across unrelated users — even users on a completely different front…
Darkham42/starsunknown
We haven't classified any articles referencing CVE-2026-33555 yet. The external references above still apply.