Header injection via unvalidated HTTP/2 values
Published Aug 20, 2026 · Updated Aug 20, 2026
CRLF injection in Bandit before 1.12.5 allows remote attackers to pass CR, LF, or NUL bytes into application-visible HTTP/2 request headers. Bandit.HTTP2.Stream.read_headers/1 validates pseudo-header order, casing, and connection-specific header rules but decodes field values from HPACK into conn.req_headers without rejecting \r, \n, or \0, and it also accepted duplicate :authority pseudo-headers until the same fix. Exposure requires HTTP/2 reachability, and impact depends on downstream code that logs or forwards header values verbatim, enabling forged log entries or malformed upstream requests rather than response splitting in Bandit itself.
Summary
What happened
CRLF injection in Bandit before 1.12.5 allows remote attackers to pass CR, LF, or NUL bytes into application-visible HTTP/2 request headers. Bandit.HTTP2.Stream.read_headers/1 validates pseudo-header order, casing, and connection-specific header rules but decodes field values from HPACK into conn.req_headers without rejecting \r, \n, or \0, and it also accepted duplicate :authority pseudo-headers until the same fix. Exposure requires HTTP/2 reachability, and impact depends on downstream code that logs or forwards header values verbatim, enabling forged log entries or malformed upstream requests rather than response splitting in Bandit itself.
The record
- CVE
- CVE-2026-75484
- Published
- Aug 20, 2026
- Updated
- Aug 20, 2026
- Vendor
- Mat Trudel
- Product
- Bandit
- Classifications
- CWE-93, CAPEC-81
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 20, 2026CVE publishedPublication date reported by the CVE source.
- Aug 20, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.4.0 <1.12.5
- Affected versionversion=fff06efe3be962b484bd4d3eb339372fda5a231f <d38cf046c9a3cae4d0f88001c2ceb4143f86366b
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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