{"id":"CVE-2023-36807","aliases":["DEBIAN-CVE-2023-36807","EUVD-2023-1823","GHSA-hm9v-vj3r-r55m","PYSEC-2026-1836","UBUNTU-CVE-2023-36807"],"status":"published","title":"Infinite Loop when reading malformed objects in pypdf","description":"pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details.","severity":{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00573,"percentile":0.47695,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-835"],"published":"2023-06-30T18:38:10Z","modified":"2026-11-04T02:46:09Z","fixes":[{"ecosystem":"PyPI","package":"pypdf2","fixed_in":["2.10.6"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:12","package":"pypdf2","fixed_in":["2.10.7-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"pypdf2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.10.5"},{"last_affected":"2.10.5"},{"fixed":"2.10.6"}]}],"versions":["2.10.5"]},{"source":"osv","ecosystem":"Debian:12","package":"pypdf2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.10.7-1"}]}]},{"source":"osv","ecosystem":"PyPI","package":"pypdf2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.10.5"},{"fixed":"2.10.6"}]}],"versions":["2.10.5"]},{"source":"osv","ecosystem":"PyPI","package":"pypdf2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.10.5"},{"fixed":"2.10.6"}]}],"versions":["2.10.5"]}],"products":[{"vendor":"py-pdf","product":"pypdf"},{"vendor":"pypdf_project","product":"pypdf"}],"references":[{"url":"https://github.com/py-pdf/pypdf/security/advisories/GHSA-hm9v-vj3r-r55m","tags":["x_refsource_CONFIRM","x_transferred","Exploit","Mitigation","Patch","Vendor Advisory","advisory","web","report"]},{"url":"https://github.com/py-pdf/pypdf/issues/1329","tags":["x_refsource_MISC","x_transferred","Exploit","Issue Tracking","Vendor Advisory","report","web"]},{"url":"https://github.com/py-pdf/pypdf/pull/1331","tags":["x_refsource_MISC","x_transferred","Patch","fix","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-36807","tags":["advisory"]},{"url":"https://github.com/py-pdf/pypdf/commit/e6531a25325e7e0174b6a1ba03b57320b5227f6b","tags":["web","fix"]},{"url":"https://github.com/advisories/GHSA-hm9v-vj3r-r55m","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/36xxx/CVE-2023-36807.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2023-36807","tags":["advisory"]},{"url":"https://github.com/py-pdf/pypdf","tags":["package"]},{"url":"https://pypi.org/project/pypdf2","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2023-36807","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-36807","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2023-36807","title":"Infinite Loop when reading malformed objects in pypdf","description":"pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details. ","status":"published","published":"2023-06-30T18:38:10.303Z","modified":"2024-11-06T19:51:43.12Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:35:27.810438Z"}],"euvd":[{"id":"EUVD-2023-1823","description":"pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details. ","status":"published","published":"2023-06-30T18:38:10Z","modified":"2024-11-06T19:51:43Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T00:05:08.721426Z"}],"ghsa":[{"id":"GHSA-hm9v-vj3r-r55m","title":"PyPDF2 vulnerable to possible Infinite Loop when reading malformed objects","description":"### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop.\nThis infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF.\n\n### Patches\nThe issue was fixed with https://github.com/py-pdf/pypdf/pull/1331\n\n### Workarounds\nIf you cannot update your version of `PyPDF2` (preferably to `pypdf\u003e3.1.0` as PyPDF2 is deprecated), you should modify `PyPDF2/generic/_data_structures.py::read_object`.\n\nReplace:\n\n```python\n    else:\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n```\n\nby\n\n```python\n    elif tok in b\"0123456789+-.\":\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n    else:\n        raise PdfReadError(\n            f\"Invalid Elementary Object starting with {tok} @{stream.tell()}\"\n        )\n```\n\n### References\n* [pypdf issue #1329](https://github.com/py-pdf/pypdf/issues/1329)\n* [pypdf PR #1331](https://github.com/py-pdf/pypdf/pull/1331)","status":"published","published":"2023-06-30T22:19:39Z","modified":"2023-11-05T05:06:44Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T14:37:14.234712Z"}],"nvd":[{"id":"CVE-2023-36807","description":"pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details. ","status":"published","published":"2023-06-30T19:15:09.283Z","modified":"2026-11-02T16:06:04.477Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T20:51:29.040079Z"}],"osv":[{"id":"CVE-2023-36807","title":"Infinite Loop when reading malformed objects in pypdf","description":"pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details. ","status":"published","published":"2023-06-30T18:38:10.303Z","modified":"2026-11-04T02:46:09.968520421Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-835"],"updated_at":"2026-11-04T02:54:00.554175Z"},{"id":"DEBIAN-CVE-2023-36807","description":"pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details.","status":"published","published":"2023-06-30T19:15:09.283Z","modified":"2026-11-03T09:47:32.714049906Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T10:27:58.933618Z"},{"id":"GHSA-hm9v-vj3r-r55m","title":"PyPDF2 vulnerable to possible Infinite Loop when reading malformed objects","description":"### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop.\nThis infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF.\n\n### Patches\nThe issue was fixed with https://github.com/py-pdf/pypdf/pull/1331\n\n### Workarounds\nIf you cannot update your version of `PyPDF2` (preferably to `pypdf\u003e3.1.0` as PyPDF2 is deprecated), you should modify `PyPDF2/generic/_data_structures.py::read_object`.\n\nReplace:\n\n```python\n    else:\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n```\n\nby\n\n```python\n    elif tok in b\"0123456789+-.\":\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n    else:\n        raise PdfReadError(\n            f\"Invalid Elementary Object starting with {tok} @{stream.tell()}\"\n        )\n```\n\n### References\n* [pypdf issue #1329](https://github.com/py-pdf/pypdf/issues/1329)\n* [pypdf PR #1331](https://github.com/py-pdf/pypdf/pull/1331)","status":"published","published":"2023-06-30T22:19:39Z","modified":"2026-07-07T17:56:23.416854613Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-835"],"updated_at":"2026-11-02T15:46:49.28217Z"},{"id":"PYSEC-2026-1836","title":"PyPDF2 vulnerable to possible Infinite Loop when reading malformed objects","description":"### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop.\nThis infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF.\n\n### Patches\nThe issue was fixed with https://github.com/py-pdf/pypdf/pull/1331\n\n### Workarounds\nIf you cannot update your version of `PyPDF2` (preferably to `pypdf\u003e3.1.0` as PyPDF2 is deprecated), you should modify `PyPDF2/generic/_data_structures.py::read_object`.\n\nReplace:\n\n```python\n    else:\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n```\n\nby\n\n```python\n    elif tok in b\"0123456789+-.\":\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n    else:\n        raise PdfReadError(\n            f\"Invalid Elementary Object starting with {tok} @{stream.tell()}\"\n        )\n```\n\n### References\n* [pypdf issue #1329](https://github.com/py-pdf/pypdf/issues/1329)\n* [pypdf PR #1331](https://github.com/py-pdf/pypdf/pull/1331)","status":"published","published":"2026-07-07T11:45:19.767457Z","modified":"2026-07-07T17:46:59.504076185Z","cvss":[{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:52:55.06457Z"},{"id":"UBUNTU-CVE-2023-36807","description":"pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details.","status":"withdrawn","published":"2023-06-30T19:15:00Z","modified":"2025-07-16T07:46:08.128122Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","level":"medium"},{"version":"3.1","score":6.2,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T16:54:21.882004Z"}]}}