VulnerabilityPublished 14 Aug 2026

CVE-2026-19879: CWE-681

Source GCVE Database

Compare

Authoritative record:CVE-2026-19879· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (redhat)	CVSS 3.1	5.3

EPSS: 0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 14 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-2crv-pxj9-66x8

What to do

Affected software

Product	Affected	Fixed in
Red Hat build of Apache Camel for Spring Boot 4undertow-core	Affected–	Fixed in–
Red Hat build of Apache Camel for Spring Boot 4undertow-parent	Affected–	Fixed in–
Red Hat build of Apache Camel for Spring Boot 4undertow-servlet	Affected–	Fixed in–
Red Hat build of Apache Camel for Spring Boot 4undertow-websockets-jsr	Affected–	Fixed in–
Red Hat Enterprise Linux 10moditect	Affected–	Fixed in–
Red Hat Enterprise Linux 8pki-core:10.6/resteasy	Affected–	Fixed in–

AI-suggested

Applications using Undertow should implement robust input validation and sanitization for all user-controlled data before placing it into HTTP response headers. It is recommended to restrict header values to printable ASCII characters (0x20–0x7E) at the application level. Where possible, use framework-provided header-safe encoding mechanisms to handle special characters properly.

Description

CVE-2026-19879 is a moderate severity vulnerability in Undertow HTTP server's response header writing path. The flaw involves the writeString() method silently narrowing 16-bit Unicode characters to 8-bit bytes, which can truncate certain Unicode characters into ASCII control characters or special symbols. This may lead to limited integrity impact or information disclosure if user input is not properly sanitized before being placed into HTTP response headers. Undertow prevents HTTP response splitting, but improper validation at the application level can pose risks.

Impact

The vulnerability can cause limited integrity impact or information disclosure by truncating Unicode characters into ASCII control characters or special symbols in HTTP response headers. This may affect applications that reflect user-controlled input in headers without proper validation. There is no impact on confidentiality or availability, and no known exploitation in the wild has been reported.

CWE-681Incorrect Conversion between Numeric Types (opens in a new tab)
Base weaknessLikelihood of exploit: High
When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.
Implementation
Avoid making conversion between numeric types. Always check for the allowed ranges.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2026, 13:43 UTC

WeaknessesCWE-681

Technical details

References

Community reviews

Related threats