CVE-2026-90678

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Source
https://cve.org/CVERecord?id=CVE-2026-90678
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90678.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-90678
Downstream
Published
2026-09-13T03:37:55Z
Modified
2026-09-14T08:02:10Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:L CVSS Calculator
Summary
[none]
Details

An issue was discovered in HAProxy 3.3.0 through 3.4.4 and in 3.5-dev1 through 3.5-dev5. Exploitation requires an HTTP/3 frontend: HAProxy must be built with QUIC support and configured with a QUIC bind listener, and the affected traffic must reach a backend over HTTP/1.1 using chunked transfer coding on a reused connection. Under those conditions, when an HTTP/3 request carries no Content-Length header, the HTTP/3 multiplexer credits the length declared in a DATA frame header to the stream endpoint's known-input-payload estimate at the moment the frame header is decoded, before the payload has been received, and that declared length is emitted verbatim as the HTTP/1.1 chunk size. A remote unauthenticated client that declares more payload than it delivers and then ends the stream causes HAProxy to announce a chunk larger than the bytes it writes and to return the connection to the idle pool in a desynchronized state. The result is potential HTTP request smuggling on reused backend connections: an attacker can place a request past a frontend rule such as a path-based http-request deny, so that the smuggled request is never seen by HAProxy's HTTP analysis, and can cause concurrent clients' requests, including their request lines and Authorization headers, to be consumed as the attacker's request body and lost. Exploitation is not deterministic; it depends on a race with backend connection pooling, succeeding in a majority of but not all trials during testing, and can be retried freely. The mechanism was introduced in 3.3-dev10; releases 3.2.x and earlier are unaffected.

Database specific 
{
    "cna_assigner": "mitre",
    "cwe_ids": [
        "CWE-130"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90678.json"
}
References

Affected packages

Git / github.com/haproxy/haproxy

Affected ranges

Type
GIT
Repo
https://github.com/haproxy/haproxy
Events
Introduced
7832fb21fe2dd11ce44e996d8e86802731b871b2
Fixed
68e9fb73fd89bc5d3a380a98f37ece3db9c41ed9
Introduced
088552ec0856a9ee2d9558b177833c1eff564a97
Fixed
03bde20ef72d40f7fd546f0725da0f787934ac1b
Fixed
86a4ebc761a278838e8cb06f3a292282ba704c65
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "3.3.0"
        },
        {
            "fixed": "3.4.4"
        },
        {
            "introduced": "3.5-dev1"
        },
        {
            "fixed": "3.5-dev5"
        }
    ],
    "source": [
        "DESCRIPTION",
        "REFERENCES"
    ]
}

Affected versions

v3.*
v3.3.0
v3.4-dev0
v3.4-dev1
v3.4-dev2
v3.4-dev3
v3.5-dev1
v3.5-dev2
v3.5-dev3
v3.5-dev4
v3.5-dev5

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90678.json"
vanir_signatures 
[
    {
        "deprecated": false,
        "digest": {
            "function_hash": "259840505773216922512812858459859185427",
            "length": 6540
        },
        "id": "CVE-2026-90678-26bb158d",
        "signature_type": "Function",
        "signature_version": "v1",
        "source": "https://github.com/haproxy/haproxy/commit/86a4ebc761a278838e8cb06f3a292282ba704c65",
        "target": {
            "file": "src/h3.c",
            "function": "h3_rcv_buf"
        }
    },
    {
        "deprecated": false,
        "digest": {
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            ],
            "threshold": 0.9
        },
        "id": "CVE-2026-90678-f54901bf",
        "signature_type": "Line",
        "signature_version": "v1",
        "source": "https://github.com/haproxy/haproxy/commit/86a4ebc761a278838e8cb06f3a292282ba704c65",
        "target": {
            "file": "src/h3.c"
        }
    }
]
vanir_signatures_modified 
"2026-09-14T08:02:10Z"