CVE-2026-84378
Publication date 3 September 2026
Last updated 4 September 2026
Ubuntu priority
Description
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| python-httpx2 | 26.04 LTS resolute | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release |
Severity score breakdown
CVSS version: CVSS v3.0
Base score
5.9 · Medium
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
References
Other references
- https://www.cve.org/CVERecord?id=CVE-2026-84378
- https://github.com/pydantic/httpx2/security/advisories/GHSA-f2fp-rgf2-35cp
- https://github.com/pydantic/httpx2/pull/1071
- https://github.com/pydantic/httpx2/pull/1117
- https://github.com/pydantic/httpx2/commit/cbfc0e04ef6507da29ccbb3b9c2e5b23dd693414
- https://github.com/pydantic/httpx2/releases/tag/v2.10.0