Form field override via unescaped multipart names
Published Jun 12, 2026 · Updated Aug 28, 2026
CRLF injection in form-data before 2.5.6, 3.0.0 through 3.0.4, and 4.0.0 through 4.0.5 allows remote attackers to alter form fields. FormData#append header builders concatenate field names and filenames into Content-Disposition without escaping CR, LF, or double quotes. Exploitation requires a consuming application to accept untrusted names; injected headers or multipart parts can change fields parsed by its backend.
Summary
What happened
CRLF injection in form-data before 2.5.6, 3.0.0 through 3.0.4, and 4.0.0 through 4.0.5 allows remote attackers to alter form fields. FormData#append header builders concatenate field names and filenames into Content-Disposition without escaping CR, LF, or double quotes. Exploitation requires a consuming application to accept untrusted names; injected headers or multipart parts can change fields parsed by its backend.
The record
- CVE
- CVE-2026-12143
- Published
- Jun 12, 2026
- Updated
- Aug 28, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat Quay
- Classifications
- CWE-93, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 12, 2026CVE publishedPublication date reported by the CVE source.
- Aug 28, 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?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream multipart header-injection proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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