# CVE-2026-93573: Io.netty/netty-codec-http: netty split transfer-encoding fields bypass final-chunked validation and enable request smuggling

Status: published. Published: 2026-09-18. Updated: 2026-11-06.

A flaw was found in Netty's HTTP/1.1 decoder. This vulnerability allows a remote attacker to bypass `Transfer-Encoding` header validation by splitting the `Transfer-Encoding` field across multiple headers, with the last field containing a non-final transfer coding like `gzip` or `deflate`. This bypass can lead to HTTP request smuggling, enabling attackers to bypass security controls, desynchronize request processing, or cause requests to be processed in an unintended context.

## Remediation

- workaround: See https://github.com/netty/netty/security/advisories/GHSA-3jrc-fchc-59pw for fixed versions and remediation guidance. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Build of Debezium 3.6 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.4 (keycloak-rhel9-container): ≥ 26.4-29; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.4 (keycloak-rhel9-operator-bundle-container): ≥ 26.4.17-2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.4 (keycloak-rhel9-operator-container): ≥ 26.4-30; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.6.8 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Quarkus 3.27.5.SP2 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Quarkus 3.33.3.SP2 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat AMQ Broker 7 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat AMQ Clients (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Apache Camel 4 for Quarkus 3 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Apache Camel for Spring Boot 4 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Apicurio Registry 3 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Data Grid 8 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Fuse 7 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 7 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8 (netty-codec-http): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Single Sign-On 7 (netty-codec-http): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N; source: CNA: redhat

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.90% as of 2026-11-05; percentile 59.69%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-444

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:69440 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:69470 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:83612 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:95760 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:95761 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-93573 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2536964 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:69440 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:69470 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:83612 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:95760 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:95761 (secalert@redhat.com)

- https://access.redhat.com/security/cve/CVE-2026-93573 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2536964 (secalert@redhat.com)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-93573; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93573; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-93573; retrieved 2026-11-06; source updated Not reported

Revision: 6b90a9dced3f6b63e1e6a43b11d178c285a8f707764efeddf6e88c67f4d4c2da

Canonical: https://y2.dev/cve/CVE-2026-93573

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.