Vulnerability-Lookup

GHSA-4VJ7-5MJ6-JM8M

Vulnerability from github – Published: 2026-07-10 14:32 – Updated: 2026-07-10 14:32

Summary

morgan vulnerable to Log Forging via unneutralized control characters in :remote-user

Details

Impact

Morgan's :remote-user token extracts the Basic auth username from the Authorization header and writes it to the log stream without neutralizing control characters. An attacker can send a crafted Authorization: Basic header containing CR/LF characters to inject forged log lines, corrupting the one-request-per-line structure of access logs.

The built-in combined, common, default, and short formats are affected, as well as any custom format that includes :remote-user.

Patches

Users should upgrade to version 1.11.0.

Workarounds

Use a custom format string that does not include :remote-user.

Severity

5.3 (Medium)


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

Show details on source website

JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.10.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "morgan"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.2.0"
            },
            {
              "fixed": "1.11.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-5078"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-117"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-10T14:32:15Z",
    "nvd_published_at": "2026-06-03T08:16:19Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nMorgan\u0027s `:remote-user` token extracts the Basic auth username from the `Authorization` header and writes it to the log stream without neutralizing control characters. An attacker can send a crafted `Authorization: Basic` header containing CR/LF characters to inject forged log lines, corrupting the one-request-per-line structure of access logs.\n\nThe built-in `combined`, `common`, `default`, and `short` formats are affected, as well as any custom format that includes `:remote-user`.\n\n### Patches\n\nUsers should upgrade to version 1.11.0.\n\n### Workarounds\n\nUse a custom format string that does not include `:remote-user`.",
  "id": "GHSA-4vj7-5mj6-jm8m",
  "modified": "2026-07-10T14:32:15Z",
  "published": "2026-07-10T14:32:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/morgan/security/advisories/GHSA-4vj7-5mj6-jm8m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-5078"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/expressjs/morgan"
    }
  ],
  "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 unneutralized control characters in :remote-user"
}

CVE-2026-5078 (GCVE-0-2026-5078)

Vulnerability from cvelistv5 – Published: 2026-06-03 05:56 – Updated: 2026-06-03 13:19

Title

morgan vulnerable to Log Forging via unneutralized control characters in :remote-user

Summary

Impact: The morgan logging middleware's :remote-user token extracts the Basic auth username from the Authorization request header and writes it to the log stream without neutralizing control characters. An unauthenticated attacker can send a crafted Authorization Basic header containing CR or LF bytes to inject forged log lines, breaking the one-request-per-line structure of access logs and enabling log forgery against downstream log consumers. The built-in combined, common, default, and short formats are affected, as well as any custom format that references :remote-user. Affected versions: morgan 1.2.0 through 1.10.1. Patches: upgrade to morgan 1.11.0, which neutralizes control characters in the :remote-user token output. Workarounds: use a custom format string that does not include :remote-user.

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 2026-06-03 13:16 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: 1.2.0 , ≤ 1.10.1 (semver) Unaffected: 1.11.0 (semver)

Credits

Yuki Matsuhashi Ulises Gascón Jon Church

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-5078",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-03T13:16:59.663217Z",
                "version": "2.0.3"
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          "type": "reporter",
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          "type": "remediation developer",
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        },
        {
          "lang": "en",
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        }
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      "metrics": [
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          "cvssV3_1": {
            "attackComplexity": "LOW",
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      "references": [
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    "dateReserved": "2026-03-28T17:42:51.328Z",
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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.

Related by attack behaviour

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