{"cve":"CVE-2026-33555","nvd":{"published":"2026-04-13T17:16:28.237","modified":"2026-10-18T20:16:48.110","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","score":5.8},"cwes":["CWE-130"],"references":["https://github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84","https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html","https://www.haproxy.com/documentation/haproxy-aloha/changelog/","https://www.haproxy.org","https://www.mail-archive.com/haproxy@formilux.org/msg46752.html"],"products":["haproxy:haproxy"],"source":"nvd","synced_at":"2026-10-19T22:30:49.762551342+00:00"},"epss":{"cve":"CVE-2026-33555","score":0.00307,"percentile":0.23322,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}