Vulnerability-Lookup

GHSA-FW87-FV5R-9FPW

Vulnerability from github – Published: 2026-06-16 20:12 – Updated: 2026-06-16 20:12

Summary

Hugo: Symlink confinement bypass in resources.Get

Details

Commit: f8b5fa09a6 — Fix prevention of direct symlink reads in resources.Get Affected versions: v0.123.0 through v0.161.1. Earlier versions are not affected. Fixed in: v0.162.0. Severity: Medium. Requires the attacker to be able to place (or convince a site author to place) a symlink inside a mounted directory — for example, inside a locally-vendored theme under themes/. Themes mounted as Go modules from GitHub have symlinks stripped on download and are not affected. Multi-directory walks (e.g. content/asset walking) were not affected either; only direct lookups via resources.Get followed symlinks.

Description. Hugo's virtual filesystem is designed so that files under a mount cannot reach outside the mount tree. A regression introduced in v0.123.0 caused RootMappingFs.statRoot to call Stat (which follows symlinks) instead of Lstat, so a direct resources.Get "somefile" where somefile was a symlink pointing outside the mount would return the target's contents. This effectively let a symlink planted inside a theme or local mount read arbitrary files reachable to the user running hugo.

Mitigation. v0.162.0 calls LstatIfPossible and rejects symlinked entries with os.ErrNotExist, matching the behaviour of pre-v0.123.0 releases and of the directory-walking code paths.

Severity

6.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/gohugoio/hugo"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.123.0"
            },
            {
              "fixed": "0.162.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-50135"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-16T20:12:34Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "**Commit:** [f8b5fa09a6](https://github.com/gohugoio/hugo/commit/f8b5fa09a6) \u2014 _Fix prevention of direct symlink reads in resources.Get_\n**Affected versions:** v0.123.0 through v0.161.1. Earlier versions are not affected.\n**Fixed in:** v0.162.0.\n**Severity:** Medium. Requires the attacker to be able to place (or convince a site author to place) a symlink inside a mounted directory \u2014 for example, inside a locally-vendored theme under `themes/`. Themes mounted as Go modules from GitHub have symlinks stripped on download and are not affected. Multi-directory walks (e.g. content/asset walking) were not affected either; only direct lookups via `resources.Get` followed symlinks.\n\n**Description.** Hugo\u0027s virtual filesystem is designed so that files under a mount cannot reach outside the mount tree. A regression introduced in v0.123.0 caused `RootMappingFs.statRoot` to call `Stat` (which follows symlinks) instead of `Lstat`, so a direct `resources.Get \"somefile\"` where `somefile` was a symlink pointing outside the mount would return the target\u0027s contents. This effectively let a symlink planted inside a theme or local mount read arbitrary files reachable to the user running `hugo`.\n\n**Mitigation.** v0.162.0 calls `LstatIfPossible` and rejects symlinked entries with `os.ErrNotExist`, matching the behaviour of pre-v0.123.0 releases and of the directory-walking code paths.",
  "id": "GHSA-fw87-fv5r-9fpw",
  "modified": "2026-06-16T20:12:34Z",
  "published": "2026-06-16T20:12:34Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gohugoio/hugo/security/advisories/GHSA-fw87-fv5r-9fpw"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gohugoio/hugo/commit/f8b5fa09a64950c32b803821ede411ebfe772b7a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gohugoio/hugo"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gohugoio/hugo/releases/tag/v0.162.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Hugo: Symlink confinement bypass in resources.Get"
}

CVE-2026-50135 (GCVE-0-2026-50135)

Vulnerability from cvelistv5 – Published: 2026-07-06 19:52 – Updated: 2026-07-07 16:57

Title

Hugo: Symlink confinement bypass in resources.Get

Summary

Hugo is a static site generator. From 0.123.0 to 0.161.1, a regression made RootMappingFs.statRoot use Stat (follows symlinks) instead of Lstat , so a direct resources.Get of a symlink pointing outside its mount returned the target's contents — letting a symlink planted in a local mount (e.g. a vendored themes/ theme) read arbitrary files accessible to the Hugo user. Go-module themes from GitHub (symlinks stripped) and directory walks were unaffected. Fixed in 0.162.0.

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-07 16:52 UTC

CWE

CWE-59 - Improper Link Resolution Before File Access ('Link Following')

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/gohugoio/hugo/security/advisor…	x_refsource_CONFIRM
https://github.com/gohugoio/hugo/commit/f8b5fa09a…	x_refsource_MISC
https://github.com/gohugoio/hugo/releases/tag/v0.162.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
gohugoio	hugo	Affected: >= 0.123.0, < 0.162.0

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-50135",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-07T16:52:31.351209Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-07T16:57:29.874Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "hugo",
          "vendor": "gohugoio",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.123.0, \u003c 0.162.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Hugo is a static site generator. From 0.123.0 to 0.161.1, a regression made \u00a0RootMappingFs.statRoot\u00a0 use \u00a0Stat\u00a0 (follows symlinks) instead of \u00a0Lstat\u00a0, so a direct \u00a0resources.Get\u00a0 of a symlink pointing outside its mount returned the target\u0027s contents \u2014 letting a symlink planted in a local mount (e.g. a vendored \u00a0themes/\u00a0 theme) read arbitrary files accessible to the Hugo user. Go-module themes from GitHub (symlinks stripped) and directory walks were unaffected. Fixed in 0.162.0."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "ACTIVE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-59",
              "description": "CWE-59: Improper Link Resolution Before File Access (\u0027Link Following\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-06T19:52:04.561Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/gohugoio/hugo/security/advisories/GHSA-fw87-fv5r-9fpw",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/gohugoio/hugo/security/advisories/GHSA-fw87-fv5r-9fpw"
        },
        {
          "name": "https://github.com/gohugoio/hugo/commit/f8b5fa09a64950c32b803821ede411ebfe772b7a",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/gohugoio/hugo/commit/f8b5fa09a64950c32b803821ede411ebfe772b7a"
        },
        {
          "name": "https://github.com/gohugoio/hugo/releases/tag/v0.162.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/gohugoio/hugo/releases/tag/v0.162.0"
        }
      ],
      "source": {
        "advisory": "GHSA-fw87-fv5r-9fpw",
        "discovery": "UNKNOWN"
      },
      "title": "Hugo: Symlink confinement bypass in resources.Get"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-50135",
    "datePublished": "2026-07-06T19:52:04.561Z",
    "dateReserved": "2026-06-03T18:49:32.275Z",
    "dateUpdated": "2026-07-07T16:57:29.874Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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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.

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.
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Action not permitted

GHSA-FW87-FV5R-9FPW

CVE-2026-50135 (GCVE-0-2026-50135)

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