CVE-2026-28351: pypdf is a free and open-source pure-python PDF library

Q: How do I fix CVE-2026-28351?

pypdf: upgrade to 6.7.4. Exact commands for each OS are on this page.

Q: Is CVE-2026-28351 being exploited?

CVE-2026-28351 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-2026-28351 affect?

CVE-2026-28351 affects pypdf. Severity is medium (CVSS 5.3). pypdf is a free and open-source pure-python PDF library. Prior to version 6.7.4, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the content stream using the RunLengthDecode f

Q: How urgent is CVE-2026-28351?

Priority 34/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-28351 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 version 6.7.4, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the content stream using the RunLengthDecode filter. This has been fixed in pypdf 6.7.4. As a workaround, consider applying the changes from PR #3664.

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 59%)
CISA exploited list	No
Weakness	CWE-400
Published	2026-02-27
Last modified	2026-11-02

Publisher (CNA): GitHub, Inc. · Vendor: py-pdf

Last updated 2026-11-02 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-02-27 21:16 UTCPublished CVE record published
2026-11-02 16:06 UTCUpdated Record last modified

py-pdf pypdf UPGRADE

Affected: < 6.7.4

Fixed in: 6.7.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 6.7.4 (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-2026-28351?

pypdf: upgrade to 6.7.4. Exact commands for each OS are on this page.

Is CVE-2026-28351 being exploited?

CVE-2026-28351 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-2026-28351 affect?

CVE-2026-28351 affects pypdf. Severity is medium (CVSS 5.3). pypdf is a free and open-source pure-python PDF library. Prior to version 6.7.4, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the content stream using the RunLengthDecode f

How urgent is CVE-2026-28351?

Priority 34/100. Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-59937 HIGH 7.5 UPGRADE pypdf is a free and open-source pure-python PDF library
CVE-2026-59935 HIGH 7.5 UPGRADE pypdf is a free and open-source pure-python PDF library
CVE-2026-59936 HIGH 7.5 UPGRADE pypdf is a free and open-source pure-python PDF library
CVE-2025-55197 HIGH 7.5 UPGRADE pypdf is a free and open-source pure-python PDF library
CVE-2026-33699 HIGH 7.5 UPGRADE pypdf is a free and open-source pure-python PDF library

References

← Back to latest CVEs