SB2026072458 - Multiple vulnerabilities in hono
Published: July 24, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 vulnerabilities.
1) HTTP response splitting (CVE-ID: CVE-2026-29086)
CWE-ID: CWE-113 - Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
CVSSv4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to manipulate cookie attributes.
The vulnerability exists due to improper neutralization of CRLF sequences in HTTP headers in the setCookie() utility when constructing the Set-Cookie header using untrusted domain or path option values. A remote attacker can supply crafted input containing semicolons, carriage returns, or newline characters to manipulate cookie attributes.
User interaction is required, and exploitation depends on an application passing user-controlled input directly into the domain or path options.
CWE-ID: CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to inject unintended SSE fields and disclose sensitive information.
The vulnerability exists due to improper neutralization of special elements in output used by a downstream component in the writeSSE() function of the Streaming Helper when processing user-controlled values in the event, id, or retry fields. A remote attacker can supply input containing carriage return and newline characters to inject unintended SSE fields and disclose sensitive information.
Applications that render event data in an unsafe manner could potentially expose themselves to client-side script injection.
3) Improper Handling of URL Encoding (Hex Encoding) (CVE-ID: CVE-2026-29045)
CWE-ID: CWE-177 - Improper Handling of URL Encoding (Hex Encoding)
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper handling of url encoding in the serveStatic handler and routing layer when handling requests for protected static resources. A remote attacker can send a specially crafted request containing encoded slashes to disclose sensitive information.
This only affects applications that protect subpaths using route-based middleware and serve files from the same static root using serveStatic. The issue does not allow access outside the static root.
Remediation
Install update from vendor's website.