CVE-2026-86252
Description
A flaw was found in h3. This vulnerability allows a remote attacker to inject arbitrary Server-Sent Events (SSE) by failing to sanitize carriage return characters in EventStream data and comment fields. Attackers can manipulate event type directives, split single push calls into multiple browser-parsed events, or escape comment fields to inject data, potentially leading to integrity issues.
Statement
This Moderate severity flaw in the h3 library, utilized by Red Hat OpenShift AI, allows for Server-Sent Events (SSE) injection. Improper sanitization of carriage return characters enables attackers to inject arbitrary SSE events, potentially leading to data manipulation or bypassing existing security controls. This issue arises from a failure to adequately sanitize input in EventStream data and comment fields.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 5.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data
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