Medium
pypdf manipulated LZWDecode streams can exhaust RAM
Type: advisorySources: OSV
pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, an attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter. This issue has been patched in version 6.4.0.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2025-66019
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 02:58 UTC · Revision 1
Source evidence
pypdf manipulated LZWDecode streams can exhaust RAM
core-osv · Original sourcePublished 25 Nov 2025, 23:38 UTC
pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, an attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter. This issue has been patched in version 6.4.0.
osv:CVE-2025-66019
Complete source record
{
"id": "f86dfc87402ba662ccddc085375e583f5ba457632b89ac263a4683cf66426525",
"url": "https://osv.dev/vulnerability/CVE-2025-66019",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "pypdf manipulated LZWDecode streams can exhaust RAM",
"summary": "pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, an attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter. This issue has been patched in version 6.4.0.",
"evidence": "osv:CVE-2025-66019",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2025-66019",
"aliases": [
"CVE-2025-66019",
"GHSA-m449-cwjh-6pw7",
"PYSEC-2026-1832"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/py-pdf/pypdf",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "310e571f2be1bc406a20b738e870d1b556d3c3a5"
},
{
"fixed": "96186725e5e6f237129a58a97cd19204a9ce40b2"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "6.4.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "96186725e5e6f237129a58a97cd19204a9ce40b2"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "310e571f2be1bc406a20b738e870d1b556d3c3a5"
}
],
"source": "REFERENCES_TAG",
"original_tag": "6.4.0"
}
]
}
}
],
"versions": [
"6.3.0",
"6.2.0",
"6.1.3",
"6.1.2",
"6.1.1",
"6.1.0",
"6.0.0",
"5.9.0",
"5.8.0",
"5.7.0",
"5.6.1",
"5.6.0",
"5.5.0",
"5.4.0",
"5.3.1",
"5.3.0",
"5.2.0",
"5.1.0",
"5.0.1",
"5.0.0",
"4.3.1",
"4.3.0",
"4.2.0",
"4.1.0",
"4.0.2",
"4.0.1",
"4.0.0",
"3.17.4",
"3.17.3",
"3.17.2",
"3.17.1",
"3.17.0",
"3.16.4",
"3.16.3",
"3.16.2",
"3.16.1",
"3.16.0",
"3.15.5",
"3.15.4",
"3.15.3",
"3.15.2",
"3.15.1",
"3.15.0",
"3.14.0",
"3.13.0",
"3.12.2",
"3.12.1",
"3.12.0",
"3.11.1",
"3.11.0",
"3.10.0",
"3.9.1",
"3.9.0",
"3.8.1",
"3.8.0",
"3.7.1",
"3.7.0",
"3.6.0",
"3.5.2",
"3.5.1",
"3.5.0",
"3.4.1",
"3.4.0",
"3.3.0",
"3.2.1",
"3.2.0",
"3.0.0",
"3.1.0",
"2.12.1",
"2.12.0",
"2.11.2",
"2.11.1",
"2.11.0",
"2.10.9",
"2.10.8",
"2.10.7",
"2.10.6",
"2.10.5",
"2.10.4",
"2.10.3",
"2.10.2",
"2.10.1",
"2.10.0",
"2.9.0",
"2.8.1",
"2.8.0",
"2.7.0",
"2.6.0",
"2.5.0",
"2.4.2",
"2.4.1",
"2.4.0",
"2.3.1",
"2.3.0",
"2.2.1",
"2.2.0",
"2.1.1",
"2.1.0",
"2.0.0",
"1.28.2",
"1.28.1",
"1.28.0",
"1.27.12",
"1.27.11",
"1.27.10",
"1.27.9",
"1.27.8",
"1.27.7",
"1.27.6",
"1.27.5",
"1.27.4",
"1.27.3",
"1.27.2",
"1.27.1",
"1.27.0",
"v1.24",
"1.26.0",
"v1.25.1",
"v1.25",
"v1.23",
"v1.22",
"v1.21",
"v1.20",
"v1.19",
"v1.18",
"v1.17"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-66019.json"
}
}
],
"modified": "2026-10-28T02:30:25.287128126Z",
"provider": "osv",
"references": [
"https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos/",
"https://github.com/py-pdf/pypdf/releases/tag/6.4.0",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66019.json",
"https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7",
"https://nvd.nist.gov/vuln/detail/CVE-2025-66019",
"https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2"
],
"provider_metadata": {
"cwe_ids": [
"CWE-400",
"CWE-409"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66019.json"
}
},
"related_cves": [
{
"value": "CVE-2025-66019",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 492069,
"published_at": "2025-11-25T23:38:12.473+00:00"
}