CVE-2026-39806

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-39806
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':do_read_chunked_data!/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 to_read, 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.

7.5 /10

CVSS v3 : HIGH

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://cna.erlef.org/cves/CVE-2026-39806.html Third Party Advisory
https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab Patch
https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf Exploit Vendor Advisory
https://osv.dev/vulnerability/EEF-CVE-2026-39806 Third Party Advisory
https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf Exploit Vendor Advisory
Configurations

Configuration 1 (hide)

cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*
History

21 May 2026, 15:23

Type Values Removed Values Added
References () https://cna.erlef.org/cves/CVE-2026-39806.html - () https://cna.erlef.org/cves/CVE-2026-39806.html - Third Party Advisory
References () https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab - () https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab - Patch
References () https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf - () https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf - Exploit, Vendor Advisory
References () https://osv.dev/vulnerability/EEF-CVE-2026-39806 - () https://osv.dev/vulnerability/EEF-CVE-2026-39806 - Third Party Advisory
CPE cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 7.5
First Time Mtrudel bandit
Mtrudel

13 May 2026, 16:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-05-13 14:17

Updated : 2026-05-21 15:23

NVD link : CVE-2026-39806

Mitre link : CVE-2026-39806

CVE.ORG link : CVE-2026-39806

JSON object : View

Products Affected

mtrudel

  • bandit
CWE
CWE-835

Loop with Unreachable Exit Condition ('Infinite Loop')