Io.undertow/undertow: undertow: http response header integrity issue due to character truncation
Priority LOW 30CWE-681Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Deferred Red Hat: fix deferred
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
A flaw was found in Undertow, an HTTP server, within its HTTP response header writing path. The `writeString()` method performs a silent narrowing cast from 16-bit Unicode characters to 8-bit bytes when writing HTTP response header values. A remote attacker can exploit this by supplying specific Unicode characters in user-controlled input that an application places into response headers. This can lead to the truncation of these characters into ASCII control characters or special symbols, potentially resulting in limited integrity impact or information disclosure if the application does not properly sanitize user input.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00393 33rd percentileScored 2026-11-07
Fix Deferred Red Hat: fix deferred
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Red Hat | Red Hat build of Apache Camel for Spring Boot 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat build of Apache Camel for Spring Boot 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat build of Apache Camel for Spring Boot 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat build of Apache Camel for Spring Boot 4 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 10 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform 8 | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | — | — | No fix listed | CNA |
| Red Hat | Red Hat JBoss Enterprise Application Platform Expansion Pack | — | — | No fix listed | CNA |
| Red Hat | Red Hat Single Sign-On 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Single Sign-On 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Single Sign-On 7 | — | — | No fix listed | CNA |
- Red Hat build of Apache Camel for Spring Boot 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat build of Apache Camel for Spring Boot 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat build of Apache Camel for Spring Boot 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat build of Apache Camel for Spring Boot 4 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform 8 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform Expansion Pack VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform Expansion Pack VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat JBoss Enterprise Application Platform Expansion Pack VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Single Sign-On 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Single Sign-On 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Single Sign-On 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
CPE names CNA · 8
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:/a:redhat:camel_spring_boot:4 | 4 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:10 | 10 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:8 | 8 | — | Red Hat |
| cpe:/a:redhat:enterprise_linux:9 | 9 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_application_platform:7 | 7 | — | Red Hat |
| cpe:/a:redhat:jboss_enterprise_application_platform:8 | 8 | — | Red Hat |
| cpe:/a:redhat:jbosseapxp | — | — | Red Hat |
| cpe:/a:redhat:red_hat_single_sign_on:7 | 7 | — | Red Hat |
- cpe:/a:redhat:camel_spring_boot:4 Versions 4 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:10 Versions 10 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:8 Versions 8 — ·Red Hat
- cpe:/a:redhat:enterprise_linux:9 Versions 9 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_application_platform:7 Versions 7 — ·Red Hat
- cpe:/a:redhat:jboss_enterprise_application_platform:8 Versions 8 — ·Red Hat
- cpe:/a:redhat:jbosseapxp Versions — — ·Red Hat
- cpe:/a:redhat:red_hat_single_sign_on:7 Versions 7 — ·Red Hat
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform 7 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform 8 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform Expansion Pack | Affected | No fix yet: Fix deferred |
| Red Hat Single Sign-On 7 | Affected | No fix yet: Fix deferred |
| Red Hat build of Apache Camel for Spring Boot 4 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-19879
- 2026-10-03 Alias added: GHSA-2crv-pxj9-66x8
References
More Red Hat vulnerabilities
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Sources
- CVE-2026-19879 · CVE Program
- CVE-2026-19879 · NVD
- FIRST EPSS
- GHSA-2crv-pxj9-66x8 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-19879 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences