EEF-CVE-2026-39803
- Source
- https://cna.erlef.org/osv/EEF-CVE-2026-39803.html
- Import Source
- https://cna.erlef.org/osv/EEF-CVE-2026-39803.json
- JSON Data
- https://api.osv.dev/v1/vulns/EEF-CVE-2026-39803
- Aliases
-
- CVE-2026-39803
- GHSA-9q9q-324x-93r2
- Published
- 2026-05-13T13:36:09.648Z
- Modified
- 2026-05-13T14:00:06.036210Z
- Severity
-
- 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS Calculator
- Summary
- HTTP/1 chunked body reader ignores length cap in bandit
- Details
-
Summary
Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion.
The chunked clause of 'Elixir.Bandit.HTTP1.Socket':readdata/2 in lib/bandit/http1/socket.ex ignores the caller-supplied :length option when reading HTTP/1 chunked request bodies. Instead of capping the accumulated body at the configured limit (e.g. Plug.Parsers' default 8 MB), doreadchunkeddata!/5 buffers every received chunk into an iolist unconditionally and materializes the entire body as a single binary. The function always returns {:ok, body, ...}, so callers cannot interpose a 413 response.
Because Plug.Parsers runs before routing and authentication in the standard Phoenix endpoint, an unauthenticated attacker needs no valid route or credentials. Sending a single Transfer-Encoding: chunked POST request with an arbitrarily large body to any path causes the BEAM process to exhaust available memory and be terminated by the OS OOM killer.
The content-length path in the same function correctly enforces the limit and is not affected.
This issue affects bandit: from 1.4.0 before 1.11.1.
- Database specific
{ "capec_ids": [ "CAPEC-130" ], "cpe_ids": [ "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*" ], "cwe_ids": [ "CWE-770" ] }- References
- Credits
-
-
- Peter Ullrich - FINDER
-
- Mat Trudel - REMEDIATION_DEVELOPER
-
- Jonatan Männchen - ANALYST
-
Affected packages
Hex / bandit
Package
- Name
- bandit
- Purl
- pkg:hex/bandit