CVE-2026-12143
HIGH 8.7form-data is a library for creating readable multipart/form-data streams. In versions through 4.0.5, the `field` argument to `FormData#append` and the `filename` option are concatenated verbatim into the `Content-Disposition` header without escaping carriage return (CR), line feed (LF), or double-quote (") characters. An application that passes attacker-controlled data as a field name or filename (for example, an API gateway that turns JSON object keys into multipart field names) allows the attacker to terminate the header line and inject additional headers, or to smuggle entire additional multipart parts, into the request the application forwards to a backend. This can let the attacker add or override form fields (e.g. set `is_admin=true`) seen by the downstream parser. This is an instance of CWE-93 (CRLF injection). The fix escapes CR, LF, and `"` as `%0D`, `%0A`, and `%22` in field names and filenames, matching the serialization browsers use per the WHATWG HTML multipart/form-data encoding algorithm. Exploitation requires the consuming application to use untrusted input as a field name or filename; applications that use only fixed/trusted field names are not affected. Fixed in 2.5.6, 3.0.5, and 4.0.6.
Severe if exploited (CVSS 8.7), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 33rd percentile
Impact if exploited
8.7CVSS 4.0 · HIGH
- ConfidentialityNone
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Affected
Products Form Data Red Hat Openshift Service Mesh 2.6 Red Hat Openshift Service Mesh 3.0 Red Hat Openshift Service Mesh 3.1 Red Hat Openshift Service Mesh 3.2 Red Hat Openshift Service Mesh 3.3 Cryostat 4 Migration Toolkit For Applications 8
Weakness (CWE)
- CWE-93
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
References
Patches & mitigations
Advisories
Technical & other
- https://www.npmjs.com/package/form-data
- https://cwe.mitre.org/data/definitions/93.html
- https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#multipart-form-data
- https://access.redhat.com/security/cve/CVE-2026-12143
- https://bugzilla.redhat.com/show_bug.cgi?id=2488480
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12143.json