# CVE-2026-75484

## Summary

- **CVE ID:** CVE-2026-75484
- **Severity:** MEDIUM
- **CVSS Score:** 6.9 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-93
- **Published:** Aug 20, 2026
- **Last Modified:** Aug 21, 2026

## Description

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.

## Affected Products

- mtrudel — bandit (1.4.0)
- mtrudel — bandit (fff06efe3be962b484bd4d3eb339372fda5a231f)

## References

- [CNA](https://github.com/mtrudel/bandit/security/advisories/GHSA-x3gh-xhj4-3vq8)
- [CNA](https://cna.erlef.org/cves/CVE-2026-75484.html)
- [CNA](https://osv.dev/vulnerability/EEF-CVE-2026-75484)
- [CNA](https://github.com/mtrudel/bandit/commit/d38cf046c9a3cae4d0f88001c2ceb4143f86366b)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.55%
- **EPSS Percentile:** 44.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._