CVE-2026-75484

What it is

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in mtrudel bandit allows an unauthenticated remote attacker to smuggle CR, LF, or NUL characters into application-visible request headers via HTTP/2. Bandit.HTTP2.Stream.read_headers/1 validates pseudo-header placement and uniqueness, header-name casing, connection-specific headers, the te value, and content-length, but never checks field values. Because HPACK carries arbitrary octets, a HEADERS block whose field values contain \r, \n, or \0 decodes without error and the values land in conn.req_headers unchanged. The HTTP/1 path already rejects the same octets; HTTP/2 did not. Bandit itself is not a sink for the injected bytes: its own logging uses fixed strings or inspect, and HTTP/2 response headers are HPACK-encoded and separately rejected by Plug's put_resp_header, so response splitting is not reachable through this path. The risk is entirely in how a downstream application consumes header values, such as appending one verbatim to a plain-text log or concatenating it into an upstream request. A related gap bundled in the same fix: only :method, :scheme, and :path were checked for at most one occurrence; a duplicate :authority pseudo-header was accepted, with the first instance silently winning as conn.host while a conflicting value remained visible to the application. This issue affects bandit: from 1.4.0 before 1.12.5.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.7% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-20 21:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-18 20:10 UTC Last updatedMost recent change to the record

Details

Published

2026-08-20 21:17 UTC

Last modified

2026-10-18 20:10 UTC

Exploit probability

0.7% · EPSS, next 30 days

Weakness

CWE-93

Record status

Awaiting Analysis

Attack profile CVSS 4.0 · 6.9

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

Low

Availability

None