CVE-2026-82398: pypdf is a free and open-source pure-python PDF library

Q: How do I fix CVE-2026-82398?

pypdf: upgrade to 6.15.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-82398 being exploited?

CVE-2026-82398 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-2026-82398 affect?

CVE-2026-82398 affects pypdf. Severity is medium (CVSS 5.3). pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without wh

Q: How urgent is CVE-2026-82398?

Priority 35/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-82398 is a medium-severity flaw (CVSS 5.3) 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 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-407
Published	2026-08-31
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

2026-08-31 22:17 UTCPublished CVE record published
2026-10-05 17:41 UTCUpdated Record last modified

pypdf project pypdf UPGRADE

Affected: < 6.15.0

Fixed in: 6.15.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 6.15.0 (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-2026-82398?

pypdf: upgrade to 6.15.0. Exact commands for each OS are on this page.

Is CVE-2026-82398 being exploited?

CVE-2026-82398 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-2026-82398 affect?

CVE-2026-82398 affects pypdf. Severity is medium (CVSS 5.3). pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without wh

How urgent is CVE-2026-82398?

Priority 35/100. Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

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References

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