morgan vulnerable to Log Injection via unescaped double quote in quoted log fields (CVE-2026-87859)
### Impact Morgan writes attacker-controlled request data to the access log. Its escaping (added in 1.11.0 and 1.12.0) neutralizes control characters, the Unicode line separators, and backslash, but not the double quote (`0x22`), which is the field delimiter of the Apache combined log format morgan emits. An attacker who controls a quoted field (`:user-agent`, `:referrer`, the request URL, or the Basic auth `:remote-user`) can inject a double quote to close the field early and forge additional fields in the log record. The `combined`, `common`, and `default` formats, and any custom format that quotes a token, are affected. This is an incomplete fix of CVE-2026-5078 and CVE-2026-15603. ### Patches Users should upgrade to version 1.12.1. ### Workarounds Update to version 1.12.1.
morgan vulnerable to Log Injection via unescaped double quote in quoted log fields (CVE-2026-87859)
Description
### Impact Morgan writes attacker-controlled request data to the access log. Its escaping (added in 1.11.0 and 1.12.0) neutralizes control characters, the Unicode line separators, and backslash, but not the double quote (`0x22`), which is the field delimiter of the Apache combined log format morgan emits. An attacker who controls a quoted field (`:user-agent`, `:referrer`, the request URL, or the Basic auth `:remote-user`) can inject a double quote to close the field early and forge additional fields in the log record. The `combined`, `common`, and `default` formats, and any custom format that quotes a token, are affected. This is an incomplete fix of CVE-2026-5078 and CVE-2026-15603. ### Patches Users should upgrade to version 1.12.1. ### Workarounds Update to version 1.12.1.
CVSS v3.1
Score 5.3medium
Affected software
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Weaknesses
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-9f6g-j8ch-79g4
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-87859"]
- Ecosystems
- ["npm"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6abb4187f7a7c54106cc2f92
Added to database: 09/29/2026, 04:41:43 UTC
Last updated: 09/29/2026, 04:41:43 UTC
Views: 1
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