Medium
pypdf: Inefficient handling of non-whitespace inputs in read_until_whitespace
Type: advisorySources: OSV
pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-82398
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 17:02 UTC · Revision 1
Source evidence
pypdf: Inefficient handling of non-whitespace inputs in read_until_whitespace
core-osv · Original sourcePublished 31 Aug 2026, 21:41 UTC
pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0.
osv:CVE-2026-82398
Complete source record
{
"id": "fd62b6525820dc1ce01c78f42c3dd825ed4cb6881b500556ab99df01d33fafe5",
"url": "https://osv.dev/vulnerability/CVE-2026-82398",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "pypdf: Inefficient handling of non-whitespace inputs in read_until_whitespace",
"summary": "pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0.",
"evidence": "osv:CVE-2026-82398",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-82398",
"aliases": [
"CVE-2026-82398",
"GHSA-fc8x-2rww-xw9m",
"PYSEC-2026-3912"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
}
],
"affected": [
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"type": "GIT",
"events": [
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],
"modified": "2026-10-28T02:30:37.999291324Z",
"provider": "osv",
"references": [
"https://github.com/py-pdf/pypdf/releases/tag/6.15.0",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82398.json",
"https://github.com/py-pdf/pypdf/security/advisories/GHSA-fc8x-2rww-xw9m",
"https://nvd.nist.gov/vuln/detail/CVE-2026-82398",
"https://github.com/py-pdf/pypdf/commit/4959848e057e37c218dccad7465259210923faaa",
"https://github.com/py-pdf/pypdf/pull/3947"
],
"provider_metadata": {
"cwe_ids": [
"CWE-407"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82398.json"
}
},
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"evidence": "/id"
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"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 505105,
"published_at": "2026-08-31T21:41:10.272+00:00"
}