CVE Explorer
CVE-2026-33555
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.
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"defaultStatus":"unaffected","product":"HAProxy","vendor":"HAProxy","versions":[{"lessThan":"3.3.6","status":"affected","version":"2.6","versionType":"custom"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"baseScore":4,"baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N","version":"3.1"},"metric_type":"cvssV3_1"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/metrics/0/cvssV3_1
CWE assertions
1 source assertion{"cweId":"CWE-130","description":"CWE-130 Improper Handling of Length Parameter Inconsistency","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/problemTypes/0/descriptions/0
Source references
6 source assertions{"url":"https://github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/references/2
{"url":"https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/references/4
{"tags":["exploit"],"url":"https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/adp/0/references/0
{"url":"https://www.haproxy.com/documentation/haproxy-aloha/changelog/"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/references/1
{"url":"https://www.haproxy.org"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/references/0
{"url":"https://www.mail-archive.com/haproxy@formilux.org/msg46752.html"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:48faf69c805303d209b431ac6746bac01ea110106e151f04d6e702fd076f3d9d · sha256:36d27332f6124a90… · /containers/cna/references/3
Attribution and limitations
- CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →
Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.