CVE-2026-33128 | h3js h3 up to 1.15.5 SSE Message formatEventStreamMessage id/event/data/comment crlf injection

VDB-352048 · CVE-2026-33128 · GCVE-0-2026-33128 H3JS H3 UP TO 1.15.5 SSE MESSAGE FORMATEVENTSTREAMMESSAGE ID/EVENT/DATA/COMMENT CRLF INJECTION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.4 $0-$5k 2.19+ Summaryinfo A vulnerability was found in h3js h3 up to 1.15.5 and classified as problematic. This issue affects the function formatEventStreamMessage of the component SSE Message Handler. Executing a manipulation of the argument id/event/data/comment can lead to crlf injection. This vulnerability appears as CVE-2026-33128. The attack may be performed from remote. There is no available exploit. It is suggested to upgrade the affected component. Detailsinfo A vulnerability has been found in h3js h3 up to 1.15.5 and classified as problematic. This vulnerability affects the function formatEventStreamMessage of the component SSE Message Handler. The manipulation of the argument id/event/data/comment with an unknown input leads to a crlf injection vulnerability. The CWE definition for the vulnerability is CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes: H3 is a minimal H(TTP) framework. In versions prior to 1.15.6 and between 2.0.0 through 2.0.1-rc.14, createEventStream is vulnerable to Server-Sent Events (SSE) injection due to missing newline sanitization in formatEventStreamMessage() and formatEventStreamComment(). An attacker who controls any part of an SSE message field (id, event, data, or comment) can inject arbitrary SSE events to connected clients. This issue is fixed in versions 1.15.6 and 2.0.1-rc.15. The advisory is shared for download at github.com. This vulnerability was named CVE-2026-33128 since 03/17/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. Upgrading to version 1.15.6 or 2.0.1-rc.15 eliminates this vulnerability. Productinfo Vendor h3js Name h3 Version 1.15.0 1.15.1 1.15.2 1.15.3 1.15.4 1.15.5 Website Product: https://github.com/h3js/h3/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 6.5 VulDB Meta Temp Score: 6.4 VulDB Base Score: 5.6 VulDB Temp Score: 5.4 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 7.5 CNA Vector (GitHub_M): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Crlf injection CWE: CWE-93 / CWE-74 / CWE-707 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: h3 1.15.6/2.0.1-rc.15 Timelineinfo 03/17/2026 CVE reserved 03/20/2026 +3 days Advisory disclosed 03/20/2026 +0 days VulDB entry created 03/20/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: github.com Status: Confirmed CVE: CVE-2026-33128 (🔒) GCVE (CVE): GCVE-0-2026-33128 GCVE (VulDB): GCVE-100-352048 Entryinfo Created: 03/20/2026 11:02 Changes: 03/20/2026 11:02 (66) Complete: 🔍 Cache ID: 99:826:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸