EEF-CVE-2026-39806

See a problem?
Please try reporting it to the source first.

Source

https://cna.erlef.org/osv/EEF-CVE-2026-39806.html

Import Source

https://cna.erlef.org/osv/EEF-CVE-2026-39806.json

JSON Data

https://api.osv.dev/v1/vulns/EEF-CVE-2026-39806

Aliases

CVE-2026-39806
GHSA-rf5q-vwxw-gmrf

Published

2026-05-13T13:36:17.806Z

Modified

2026-05-13T13:56:39.607670583Z

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 decoder infinite loop on requests with trailer fields in bandit

Details

Summary

Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in mtrudel bandit allows unauthenticated remote denial of service via worker process exhaustion.

'Elixir.Bandit.HTTP1.Socket':doreadchunkeddata!/5 in lib/bandit/http1/socket.ex terminates only when the last-chunk line 0\r\n is followed immediately by the empty trailer line \r\n. RFC 9112 §7.1.2 permits zero or more trailer fields between them. When trailers are present, none of the match clauses fit: the catch-all arm computes a negative toread, calls read_available!/2, receives <<>> on timeout, and tail-recurses with unchanged state. The worker process is pinned for the lifetime of the TCP connection.

A handful of concurrent connections sending RFC-conformant chunked requests with trailer fields is sufficient to exhaust the Bandit worker pool and render the server unresponsive to all further traffic. No authentication, special headers, or large payload is required. Proxies such as NGINX and HAProxy legitimately forward trailer-bearing requests, so servers behind such proxies may be affected without any malicious client involvement.

This issue affects bandit: from 1.6.1 before 1.11.1.

Database specific

{
    "capec_ids": [
        "CAPEC-469"
    ],
    "cpe_ids": [
        "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"
    ],
    "cwe_ids": [
        "CWE-835"
    ]
}

References

Credits

- Peter Ullrich - FINDER
- Mat Trudel - REMEDIATION_DEVELOPER
- Jonatan Männchen - ANALYST

Affected packages

Hex / bandit

Package

Name: bandit
Purl: pkg:hex/bandit

Affected ranges

Type: SEMVER
Events: Introduced

1.6.1

Fixed

1.11.1

Affected versions

1.*

1.6.1

1.6.2

1.6.3

1.6.4

1.6.5

1.6.6

1.6.7

1.6.8

1.6.9

1.6.10

1.6.11

1.7.0

1.8.0

1.9.0

1.10.0

1.10.1

1.10.2

1.10.3

1.10.4

1.11.0

Database specific

source

"https://cna.erlef.org/osv/EEF-CVE-2026-39806.json"

Git / github.com/mtrudel/bandit