pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams

{
  "id": "3ca678a279eb1ab5aeba2c90d6ac944d64e496b1ca7d2bec148fc41c48cce1f9",
  "url": "https://osv.dev/vulnerability/CVE-2026-27628",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "pypdf has a possible infinite loop when loading circular /Prev entries in cross-reference streams",
    "summary": "pypdf is a free and open-source pure-python PDF library. Prior to 6.7.2, an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading the file. This has been fixed in pypdf 6.7.2. As a workaround, one may apply the patch manually.",
    "evidence": "osv:CVE-2026-27628",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-27628",
      "aliases": [
        "CVE-2026-27628",
        "GHSA-2rw7-x74f-jg35",
        "PYSEC-2026-3005"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/py-pdf/pypdf",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4f1260f1d0c0c7c307f03e88257f8eeb229d5954"
                },
                {
                  "fixed": "f0a462d36971cf077d74492a348d0d06fd60ea4d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:pypdf_project:pypdf:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "6.7.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "f0a462d36971cf077d74492a348d0d06fd60ea4d"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27628.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.998297715Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27628.json",
        "https://github.com/py-pdf/pypdf/security/advisories/GHSA-2rw7-x74f-jg35",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-27628",
        "https://github.com/py-pdf/pypdf/issues/3654",
        "https://github.com/py-pdf/pypdf/commit/f0a462d36971cf077d74492a348d0d06fd60ea4d"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-835"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27628.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-27628",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519235,
  "published_at": "2026-02-25T02:45:37.543+00:00"
}