VulnerabilityPublished 10 Jan 2026Updated 12 Jan 2026

CVE-2026-22690: py-pdf pypdf · Uncontrolled Resource Consumption

Affects py-pdf pypdfSource CVE Database V5

Not known to be exploited · CVSS 2.7 Low : upgrade to 6.6.0 when convenient.

Data as of 26 Oct 2026, 11:07 UTC

CVSS 4.0 base score

2.7Low

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 6.6.0

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/E:U

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: Unreported

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: Unreported: Based on threat intelligence sources each of the following must apply: · No knowledge of publicly available proof-of-concept · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade py-pdf pypdf to 6.6.0.

Affected software

Product	Affected	Fixed in
py-pdfpypdf	Affected <6.6.0	Fixed in 6.6.0
PyPIpypdf`pkg:pypi/pypdf`Other threats	Affected <6.6.0	Fixed in 6.6.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate this vulnerability, European organizations should immediately upgrade all instances of pypdf to version 6.6.0 or later, where the issue is patched. Additionally, implement strict input validation and sanitization for all PDF files before processing, including rejecting PDFs missing mandatory structural elements like the /Root object. Employ resource usage monitoring and limits on PDF parsing operations to detect and prevent excessive CPU or memory consumption. Consider running PDF processing tasks in isolated environments or containers with resource constraints to limit the impact of potential abuse. For web-facing services, apply rate limiting and file size restrictions on PDF uploads to reduce attack surface. Regularly audit and update dependencies to ensure all libraries are current and vulnerabilities are addressed promptly. Finally, educate developers and system administrators about this vulnerability to ensure awareness and proactive defense.

Description

### Impact An attacker who exploits this vulnerability can craft a PDF which leads to possibly long runtimes for actually invalid files. This can be achieved by omitting the `/Root` entry in the trailer, while using a rather large `/Size` value. Only the non-strict reading mode is affected. ### Patches This has been fixed in [pypdf==6.6.0](https://github.com/py-pdf/pypdf/releases/tag/6.6.0). ### Workarounds ```python from pypdf import PdfReader, PdfWriter # Instead of reader = PdfReader("file.pdf") # use the strict mode: reader = PdfReader("file.pdf", strict=True) # Instead of writer = PdfWriter(clone_from="file.pdf") # use an explicit strict reader: writer = PdfWriter(clone_from=PdfReader("file.pdf", strict=True)) ``` ### Resources This issue has been fixed in #3594.

Impact

For European organizations, the primary impact of this vulnerability is the risk of denial-of-service conditions in systems that rely on pypdf for PDF processing, such as document management systems, automated workflows, or web services that accept PDF uploads. Attackers can exploit this flaw to degrade service availability by sending specially crafted PDFs that cause excessive resource consumption. This can lead to increased CPU usage, memory exhaustion, and potential service outages, affecting business continuity and user experience. Confidentiality and integrity are not directly impacted, but availability degradation can disrupt critical document processing operations. Organizations handling large volumes of PDFs or providing PDF-related services are particularly at risk. Additionally, sectors with high reliance on automated document workflows, such as finance, legal, and government agencies, may face operational disruptions. While the CVSS score is low, the ease of exploitation and potential for service disruption warrant attention, especially in environments processing untrusted or external PDF files.

Summary

CVE-2026-22690 is a vulnerability classified under CWE-400 (Uncontrolled Resource Consumption) affecting the pypdf library, a widely used pure-Python PDF processing tool. The issue arises in versions prior to 6.6.0 when the library processes PDF files in non-strict reading mode. Specifically, if a PDF file is crafted without the mandatory /Root object in its trailer dictionary but includes a large /Size value, pypdf attempts to process an excessive number of objects, leading to prolonged runtimes. This can cause significant CPU and memory consumption, effectively resulting in a denial-of-service (DoS) condition. The vulnerability does not require any privileges, user interaction, or authentication, and can be exploited remotely by supplying a malicious PDF to an application using the vulnerable pypdf version. The flaw is due to insufficient validation of the trailer dictionary and the /Size parameter, which controls the number of indirect objects the parser attempts to read. The issue has been addressed in pypdf version 6.6.0 by adding proper validation and limiting resource consumption during parsing. No known exploits have been reported in the wild to date, but the vulnerability poses a risk to any automated system that processes untrusted PDF files using vulnerable pypdf versions.

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Jan 2026, 07:53 UTC

WeaknessesCWE-400

Technical details

References

Community reviews

Related threats