An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used.
This has been fixed in pypdf==6.7.1.
If you cannot upgrade yet, consider applying the changes from PR #3644.
{
"nvd_published_at": "2026-02-20T22:16:29Z",
"github_reviewed_at": "2026-02-18T22:41:24Z",
"github_reviewed": true,
"severity": "MODERATE",
"cwe_ids": [
"CWE-770"
]
}