CVE-2026-22691: py-pdf pypdf Uncontrolled Resource Consumption
Vulnerability summary
CVE-2026-22691 is a medium (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in py-pdf pypdf. EPSS estimates a 0.43% chance of exploitation in the next 30 days, higher than 36.3% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 0 · Related 1Timeline
- 10-01-2026PublishedVulnerability first disclosed.
- 12-01-2026Last modifiedVulnerability information updated.
Description
pypdf is a free and open-source pure-python PDF library. Prior to version 6.6.0, pypdf has possible long runtimes for malformed startxref. An attacker who uses this vulnerability can craft a PDF which leads to possibly long runtimes for invalid startxref entries. When rebuilding the cross-reference table, PDF files with lots of whitespace characters become problematic. Only the non-strict reading mode is affected. Only the non-strict reading mode is affected. This issue has been patched in version 6.6.0.
CVSS metrics
7 scores · 5 sources · 2 versions- OSV · PypiEcosystem advisory · calculated6.9MediumCVSS: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:UDiffers
- OSV · UbuntuEcosystem advisory · calculated6.9MediumCVSS: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:UDiffers
- NVDNIST2.7LowCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · UbuntuEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- OSV · DebianEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS trend
Probability
0.43%
Chance of exploitation in the next 30 days
Percentile
36%
Versus all other CVEs
30-day change
-0.01 pp
From 0.44% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-400Uncontrolled Resource ConsumptionThe product does not properly control the allocation and maintenance of a limited resource.
- CWE-1333Inefficient Regular Expression ComplexityThe product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Affected systems
Debian2 products
- pypdfAll versions (No fix recorded) | < 6.9.0-1
- pypdf2All versions (No fix recorded)
Ubuntu2 products
- pypdfAll versions (No fix recorded)
- pypdf2All versions (No fix recorded)
Py-pdf1 product
- pypdf< 6.6.0
Pypdf_project1 product
- pypdf< 6.6.0
PyPI1 product
- pypdf< 6.6.0
5 vendors · 7 products
References
11 links- github.com/py-pdf/pypdf/security/advisories/GHSA-4f6g-68pf-7vhvX Refsource CONFIRMWEBREPORTMitigationVendor Advisory
- github.com/py-pdf/pypdf/commit/294165726b646bb7799be1cc787f593f2fdbcf45X Refsource MISCWEBREPORTPatch
- github.com/py-pdf/pypdfPACKAGE
- pypi.org/project/pypdfPACKAGE
