CVE-2026-119203— pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer search

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 6.21.4 版本之前，当 pypdf 打开一个精心构造的不完整 PDF 文件时，如果其标准交叉引用表（xref table）延伸至文件末尾却缺少结尾部分（trailer），则可能陷入无限循环。此时，trailer 搜索过程会反复回退到相同的流位置，而不是在解析无法取得进展时终止，从而导致处理线程被阻塞。该问题已在 6.21.4 版本中修复。

CVSS 7.1 · High Updated Oct 30, 2026

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Get alerts for future matching vulnerabilities Log in to subscribe

Vulnerability Information

Have questions about the vulnerability? See if Shenlong's analysis helps!

View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title

pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer search

Source: CVE Program / CVE List V5

Vulnerability Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

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

不可达退出条件的循环(无限循环)

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
py-pdf	pypdf	< 6.21.4	-

II. Public POCs for CVE-2026-119203

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

No public POC found.

III. Intelligence Information for CVE-2026-119203

请登录查看更多情报信息。

Other References for CVE-2026-119203 (4)

https://github.com/py-pdf/pypdf/pull/4289 x_refsource_MISC
https://github.com/py-pdf/pypdf/releases/tag/6.21.4 x_refsource_MISC
https://github.com/py-pdf/pypdf/security/advisories/GHSA-5849-834g-hvw5 x_refsource_CONFIRM
https://github.com/py-pdf/pypdf/commit/06593f993789a4b573dd955730c1a7051128bb2a x_refsource_MISC

https://www.cve.org/CVERecord?id=CVE-2026-119203

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-2026-119204	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-2026-119209	7.1 HIGH	pypdf: Possible large memory usage when parsing cross-reference streams
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-835