CVE-2026-84378

See a problem?
Please try reporting it to the source first.
Source
https://cve.org/CVERecord?id=CVE-2026-84378
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-84378.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-84378
Aliases
  • GHSA-f2fp-rgf2-35cp
Downstream
Published
2026-09-02T17:54:19.431Z
Modified
2026-09-04T03:46:31.456347894Z
Severity
  • 5.9 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
HTTPX2: Quadratic SSE line buffering can cause CPU denial of service
Details

HTTPX2 is a next generation HTTP client for Python. From 2.5.0 until 2.10.0, the HTTPX2 Server-Sent Events parser in src/httpx2/httpx2/_sse.py repeatedly copies and rescans buffered text in _SSELineDecoder.decode() when an attacker-controlled or compromised SSE endpoint splits one unterminated line across many response chunks. The behavior affects httpx2.Client.sse() and httpx2.AsyncClient.sse(), and the total processing work grows quadratically with the line length, allowing a crafted stream to consume excessive CPU and block a synchronous worker or asynchronous event loop. This issue is fixed in version 2.10.0.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84378.json",
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-407"
    ]
}
References

Affected packages

Git / github.com/pydantic/httpx2

Affected ranges

Type
GIT
Repo
https://github.com/pydantic/httpx2
Events
Introduced
9b7ee8ec8c06e8f35a9e7fb437c6fb2f552108bf
Fixed
cbfc0e04ef6507da29ccbb3b9c2e5b23dd693414
Fixed
a966320e75477b8c55ee78fdb8f57ead6a574cb0
Database specific
Show details 
{
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ],
    "extracted_events": [
        {
            "introduced": "2.5.0"
        },
        {
            "fixed": "2.10.0"
        }
    ]
}

Affected versions

v2.*
v2.5.0
v2.6.0
v2.7.0
v2.8.0
v2.9.0
v2.9.1

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-84378.json"