{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "0.19.18"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "f32dd84d04541f8a94fee29d1f47f3f8eeaec0be"
            }
          ],
          "repo": "https://github.com/lemmynet/lemmy",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-h6hf-9846-xwrq"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-918"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42181.json"
  },
  "details": "Lemmy is a link aggregator and forum for the fediverse. Prior to version 0.19.18, Lemmy fetches metadata for user-supplied post URLs and, under the default StoreLinkPreviews image mode, downloads the preview image through local pict-rs. While the top-level page URL is checked against internal IP ranges, the extracted og:image URL is not subject to the same restriction. As a result, an authenticated low-privileged user can submit an attacker-controlled public page whose Open Graph image points to an internal image endpoint. Lemmy will fetch that internal image server-side and store a local thumbnail that can then be served back to users. This issue has been patched in version 0.19.18.",
  "id": "CVE-2026-42181",
  "modified": "2026-07-15T01:48:56.526560302Z",
  "published": "2026-05-08T19:26:07.763Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/LemmyNet/lemmy/releases/tag/0.19.18"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42181.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42181"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Lemmy: SSRF and internal image disclosure in post link metadata via unvalidated og:image"
}