CVE-2026-39410: CWE-20: Improper Input Validation in honojs hono
A vulnerability in honojs hono versions prior to 4. 12. 12 allows bypassing cookie prefix protections due to inconsistent handling of cookie names between browser parsing and the parse() function. This discrepancy can enable attacker-controlled cookies to override legitimate cookies by normalizing distinct browser cookie names to the same key. The issue is fixed in version 4. 12. 12. The CVSS score is 4. 8, indicating a medium severity level.
AI Analysis
Technical Summary
CVE-2026-39410 describes an improper input validation vulnerability (CWE-20) in the honojs hono web application framework before version 4.12.12. The vulnerability arises from a mismatch between how browsers parse cookie names and how the parse() function in hono normalizes them. This allows an attacker to craft cookies with names that appear distinct to the browser but are normalized to the same key internally, thereby bypassing cookie prefix protections and potentially overriding legitimate cookies. This can lead to limited confidentiality and integrity impacts. The vulnerability has a CVSS 3.1 base score of 4.8 (medium severity). The issue is resolved in hono version 4.12.12.
Potential Impact
The vulnerability allows attacker-controlled cookies to override legitimate cookies by exploiting differences in cookie name parsing and normalization. This can lead to limited confidentiality and integrity impacts, such as unauthorized access or manipulation of cookie-based data. There is no indication of availability impact. No known exploits are reported in the wild.
Mitigation Recommendations
Upgrade honojs hono to version 4.12.12 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is indicated. Patch status is not explicitly stated but the fix is included in version 4.12.12.
CVE-2026-39410: CWE-20: Improper Input Validation in honojs hono
Description
A vulnerability in honojs hono versions prior to 4. 12. 12 allows bypassing cookie prefix protections due to inconsistent handling of cookie names between browser parsing and the parse() function. This discrepancy can enable attacker-controlled cookies to override legitimate cookies by normalizing distinct browser cookie names to the same key. The issue is fixed in version 4. 12. 12. The CVSS score is 4. 8, indicating a medium severity level.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-39410 describes an improper input validation vulnerability (CWE-20) in the honojs hono web application framework before version 4.12.12. The vulnerability arises from a mismatch between how browsers parse cookie names and how the parse() function in hono normalizes them. This allows an attacker to craft cookies with names that appear distinct to the browser but are normalized to the same key internally, thereby bypassing cookie prefix protections and potentially overriding legitimate cookies. This can lead to limited confidentiality and integrity impacts. The vulnerability has a CVSS 3.1 base score of 4.8 (medium severity). The issue is resolved in hono version 4.12.12.
Potential Impact
The vulnerability allows attacker-controlled cookies to override legitimate cookies by exploiting differences in cookie name parsing and normalization. This can lead to limited confidentiality and integrity impacts, such as unauthorized access or manipulation of cookie-based data. There is no indication of availability impact. No known exploits are reported in the wild.
Mitigation Recommendations
Upgrade honojs hono to version 4.12.12 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is indicated. Patch status is not explicitly stated but the fix is included in version 4.12.12.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-07T00:23:30.595Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d672521cc7ad14da85d658
Added to database: 4/8/2026, 3:20:50 PM
Last enriched: 4/8/2026, 3:35:47 PM
Last updated: 4/8/2026, 5:09:56 PM
Views: 5
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