CVE-2026-102997: pypdf is a free and open-source pure-python PDF library

Q: How do I fix CVE-2026-102997?

pypdf: upgrade to 6.18.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-102997 being exploited?

CVE-2026-102997 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-102997 affect?

CVE-2026-102997 affects pypdf. Severity is high (CVSS 7.5). pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the

Q: How urgent is CVE-2026-102997?

Priority 38/100. High severity; Remotely exploitable, no login, no user action

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-102997 is a high-severity flaw (CVSS 7.5) affecting pypdf. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This i

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 73%)
CISA exploited list	No
Weakness	CWE-400, CWE-407
Published	2026-09-30
Last modified	2026-10-05

Publisher (CNA): GitHub, Inc. · Vendor: pypdf project

Last updated 2026-10-05 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-30 21:17 UTCPublished CVE record published
2026-10-05 15:07 UTCUpdated Record last modified

pypdf project pypdf UPGRADE

Affected: < 6.18.1

Fixed in: 6.18.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy pypdf || rpm -q pypdf || pypdf --version

2. UPGRADE to 6.18.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade pypdf

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade pypdf

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-102997?

pypdf: upgrade to 6.18.1. Exact commands for each OS are on this page.

Is CVE-2026-102997 being exploited?

CVE-2026-102997 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-102997 affect?

CVE-2026-102997 affects pypdf. Severity is high (CVSS 7.5). pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the

How urgent is CVE-2026-102997?

Priority 38/100. High severity; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

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References

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