Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.7 · CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-59921: 0.46% estimated exploitation activity in the next 30 days; percentile 40.33 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Security Vulnerability Report: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder 1. Vulnerability Summary | Field | Value | |-------|-------| | Product | Netty | | Version | 4.2.12.Final (and all prior versions with codec-http multipart) | | Component | io.netty.handler.codec.http.multipart.HttpPostRequestEncoder | | Vulnerability Type | CWE-93: Improper Neutralization of CRLF Sequences / CWE-113: HTTP Response Splitting | | Impact | MIME Header Injection / Content-Type Spoofing / XSS via Content-Disposition | | CVSS 3.1 Score | 8.1 (High) | | CVSS 3.1 Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N | | Attack Vector | Network | | Attack Complexity | Low | | Privileges Required | Low (attacker must be able to upload files with controlled filenames) | | User Interaction | None | | Scope | Unchanged | | Confidentiality Impact | High | | Integrity Impact | High | | Availability Impact | None | 2. Affected Components The following classes in the codec-http…

Published by the source

22 Jul 2026, 21:52 UTC

Last modified by the source

22 Jul 2026, 21:52 UTC

Source last checked

26 Oct 2026, 16:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gcjf-9mgh-3p7g

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# Patch Next advisory brief: CVE-2026-59921

Advisory: Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder
IDs: CVE-2026-59921, GHSA-gcjf-9mgh-3p7g
Record: https://patchnext.com/advisories/cve-2026-59921 (revision 1, source checked 26 Oct 2026, 16:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.netty:netty-codec-http 4.2.16.Final, 4.1.136.Final. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.netty:netty-codec-http: affected >= 4.2.0.Final, < 4.2.16.Final; < 4.1.136.Final; fixed in 4.2.16.Final, 4.1.136.Final

## Suggested inspection (read-only)
- Maven io.netty:netty-codec-http: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on io.netty:netty-codec-http.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-gcjf-9mgh-3p7g (GitHub-reviewed advisory GHSA-gcjf-9mgh-3p7g lists affected ranges: Maven io.netty:netty-codec-http >=4.2.0.Final =0 <4.1.136.Final)

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