Vulnerability-Lookup

GHSA-JXFW-X594-9X9M

Vulnerability from github – Published: 2026-09-08 21:28 – Updated: 2026-09-08 21:28

Summary

morgan vulnerable to Log Forging via unescaped Unicode line separators

Details

Impact

Morgan writes attacker-controlled request data to the access log through its tokens. The 1.11.0 fix neutralizes C0 control characters, DEL, and backslash, but it does not escape the Unicode line separators U+0085 (NEL), U+2028 (LINE SEPARATOR), or U+2029 (PARAGRAPH SEPARATOR). These code points are reachable through several tokens, including the request URL (:url), request headers such as :user-agent and :referrer, arbitrary :req[header] values, and the Basic auth username (:remote-user). NEL is valid obs-text in HTTP header values, so an attacker can place it in an ordinary request header.

When such a value is logged, the raw code points survive into the emitted access-log record, and downstream ECMAScript-aware or Unicode-aware log processing splits the single physical record into multiple logical records. This allows an attacker to forge log entries. The built-in combined, common, default, and short formats are affected, as well as any custom format. This is an incomplete fix of CVE-2026-5078.

Patches

Users should upgrade to version 1.12.0.

Workarounds

None. The affected values include the request URL and request headers, which are core to access logging, so there is no practical format-based mitigation. Upgrade to 1.12.0.

Severity

5.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "morgan"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.12.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-15603"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-117"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-08T21:28:26Z",
    "nvd_published_at": "2026-08-28T16:17:07Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nMorgan writes attacker-controlled request data to the access log through its tokens. The 1.11.0 fix neutralizes C0 control characters, DEL, and backslash, but it does not escape the Unicode line separators `U+0085` (NEL), `U+2028` (LINE SEPARATOR), or `U+2029` (PARAGRAPH SEPARATOR). These code points are reachable through several tokens, including the request URL (`:url`), request headers such as `:user-agent` and `:referrer`, arbitrary `:req[header]` values, and the Basic auth username (`:remote-user`). NEL is valid `obs-text` in HTTP header values, so an attacker can place it in an ordinary request header.\n\nWhen such a value is logged, the raw code points survive into the emitted access-log record, and downstream ECMAScript-aware or Unicode-aware log processing splits the single physical record into multiple logical records. This allows an attacker to forge log entries. The built-in `combined`, `common`, `default`, and `short` formats are affected, as well as any custom format. This is an incomplete fix of CVE-2026-5078.\n\n### Patches\n\nUsers should upgrade to version 1.12.0.\n\n### Workarounds\n\nNone. The affected values include the request URL and request headers, which are core to access logging, so there is no practical format-based mitigation. Upgrade to 1.12.0.",
  "id": "GHSA-jxfw-x594-9x9m",
  "modified": "2026-09-08T21:28:26Z",
  "published": "2026-09-08T21:28:26Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/morgan/security/advisories/GHSA-jxfw-x594-9x9m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15603"
    },
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/morgan/commit/fbf93833186920cc39bb19b247e4a86b61bef4fe"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/expressjs/morgan"
    },
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/morgan/releases/tag/1.12.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "morgan vulnerable to Log Forging via unescaped Unicode line separators"
}

CVE-2026-15603 (GCVE-0-2026-15603)

Vulnerability from cvelistv5 – Published: 2026-08-28 13:41 – Updated: 2026-08-28 18:23

Title

morgan vulnerable to Log Forging via unescaped Unicode line separators

Summary

morgan is an HTTP request logger middleware for Node.js. In versions prior to 1.12.0, the internal helper that escapes log token values did not neutralize the Unicode line separator characters U+0085 (Next Line), U+2028 (Line Separator), and U+2029 (Paragraph Separator). An unauthenticated remote client can place these characters in an attacker-controlled log token, for example a Basic auth username surfaced through the remote-user token, so that Unicode-aware downstream log processing splits a single request log into multiple logical records. This is a log forging issue (CWE-117) and an incomplete-fix follow-up to CVE-2026-5078, which only addressed ASCII control characters. The issue is fixed in morgan 1.12.0, which extends the escaping set to cover these Unicode line separators. Upgrade to morgan 1.12.0 to remediate.

Severity

5.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-28 18:23 UTC

CWE

CWE-117 - Improper Output Neutralization for Logs

Assigner

openjs redhat root

References

2 references

URL	Tags
https://github.com/expressjs/morgan/security/advi…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
morgan	morgan	Affected: 0 , < 1.12.0 (semver)

Credits

mfazrinizar UlisesGascon jonchurch bjohansebas iaohkut-from-NightWolf-Team

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JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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