CVE-2026-119209— pypdf: Possible large memory usage when parsing cross-reference streams

Quick assessment

Affected

py-pdf pypdf

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

pypdf 是一个免费且开源的纯 Python PDF 库。在 6.21.3 版本之前，pypdf 在打开包含交叉引用流的特制 PDF 文件时，可能因这些流声明了极大的条目数量而导致内存过度消耗。高可压缩性流和 /Prev 链可成倍增加整个文档中解析的条目数量，而负的 /Index 计数则可绕过现有的每流限制机制。该问题已在 6.21.3 版本中修复。

CVSS 7.1 · High Updated Oct 30, 2026

Possible ATT&CK Techniques 1 AI

T1499.003 · Application Exhaustion Flood

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Vulnerability Information

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Vulnerability Title

pypdf: Possible large memory usage when parsing cross-reference streams

Source: CVE Program / CVE List V5

Vulnerability Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can consume excessive memory while opening a crafted PDF containing cross-reference streams that declare very large entry counts. Highly compressible streams and /Prev chains can multiply the number of parsed entries across a document, while negative /Index counts can bypass the existing per-stream clamp. This issue is fixed in version 6.21.3.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Source: CVE Program / CVE List V5

Vulnerability Type

未加控制的资源消耗(资源穷尽)

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
py-pdf	pypdf	< 6.21.3	-

II. Public POCs for CVE-2026-119209

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-119209

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Other References for CVE-2026-119209 (4)

https://github.com/py-pdf/pypdf/pull/4269 x_refsource_MISC
https://github.com/py-pdf/pypdf/releases/tag/6.21.3 x_refsource_MISC
https://github.com/py-pdf/pypdf/security/advisories/GHSA-x3rh-gjgm-fmqc x_refsource_CONFIRM
https://github.com/py-pdf/pypdf/commit/a93fe3a901fd00af38f0a105c3ba7175fa72dcb4 x_refsource_MISC

https://www.cve.org/CVERecord?id=CVE-2026-119209

Same Patch Batch · py-pdf · 2026-10-29 · 7 CVEs total

CVE-2026-119206	7.1 HIGH	pypdf: Possible long runtimes when retrieving page labels
CVE-2026-119203	7.1 HIGH	pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer searc
CVE-2026-119204	7.1 HIGH	pypdf: Possible large memory usage when parsing page tree
CVE-2026-119207	7.1 HIGH	pypdf: Possible large memory usage for exceptions in strict mode
CVE-2026-119205	7.1 HIGH	pypdf: Possible infinite loop when cloning dictionaries
CVE-2026-119208	7.1 HIGH	pypdf: Possible long runtimes/large memory usage for encrypted PDF files

IV. Related Vulnerabilities

Same product: pypdf

Same vendor: py-pdf

Same weakness: CWE-400