Vulnerability · Published Aug 14, 2026 · Assigned by redhat

CVE-2026-19879Io.undertow/undertow: undertow: http response header integrity issue due to character truncation

Medium 5.3

In plain English

A medium-severity security flaw in Red Hat build of Apache Camel for Spring Boot 4 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.4%top 66.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:14	undertow	no fix listed	DEBIAN-CVE-2026-19879
Ubuntu:26.04:LTS	undertow	no fix listed	UBUNTU-CVE-2026-19879
Ubuntu:26.10	undertow	no fix listed	UBUNTU-CVE-2026-19879

Affected products (as reported)

Vendor	Product	Versions
Red Hat	Red Hat build of Apache Camel for Spring Boot 4	see references
Red Hat	Red Hat build of Apache Camel for Spring Boot 4	see references
Red Hat	Red Hat build of Apache Camel for Spring Boot 4	see references
Red Hat	Red Hat build of Apache Camel for Spring Boot 4	see references
Red Hat	Red Hat Enterprise Linux 10	see references
Red Hat	Red Hat Enterprise Linux 8	see references
Red Hat	Red Hat Enterprise Linux 8	see references
Red Hat	Red Hat Enterprise Linux 9	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 7	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 7	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 7	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 7	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 7	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 7	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 7	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 8	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 8	see references
Red Hat	Red Hat JBoss Enterprise Application Platform 8	see references
Red Hat	Red Hat JBoss Enterprise Application Platform Expansion Pack	see references
Red Hat	Red Hat JBoss Enterprise Application Platform Expansion Pack	see references
Red Hat	Red Hat JBoss Enterprise Application Platform Expansion Pack	see references
Red Hat	Red Hat Single Sign-On 7	see references
Red Hat	Red Hat Single Sign-On 7	see references
Red Hat	Red Hat Single Sign-On 7	see references

Weakness: CWE-681 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References

https://access.redhat.com/security/cve/CVE-2026-19879 vdb-entry, x_refsource_REDHAT
RHBZ#2516038 issue-tracking, x_refsource_REDHAT