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CVE-2025-66019

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.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:ee64ae88a5f804436ba8218ee19d738e2510de6704f1eac027af2b8b5916186a
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-409","description":"CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/problemTypes/1/descriptions/0

{"cweId":"CWE-400","description":"CWE-400: Uncontrolled Resource Consumption","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/problemTypes/0/descriptions/0

Affected products and versions

1 source assertion
{"product":"pypdf","vendor":"py-pdf","versions":[{"status":"affected","version":"< 6.4.0"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":6.6,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"metric_type":"cvssV4_0"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/metrics/0/cvssV4_0

CWE assertions

2 source assertions
{"cweId":"CWE-409","description":"CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/problemTypes/1/descriptions/0
{"cweId":"CWE-400","description":"CWE-400: Uncontrolled Resource Consumption","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/problemTypes/0/descriptions/0

Source references

4 source assertions
{"url":"https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos/"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/adp/1/references/0
{"name":"https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2","tags":["x_refsource_MISC"],"url":"https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/references/1
{"name":"https://github.com/py-pdf/pypdf/releases/tag/6.4.0","tags":["x_refsource_MISC"],"url":"https://github.com/py-pdf/pypdf/releases/tag/6.4.0"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/references/2
{"name":"https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7","tags":["x_refsource_CONFIRM"],"url":"https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:5ababa5d12af5d80731d9892785680967ebe4ef460b367165c1b74ffa50eac8c · sha256:9faef25e23290566… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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