CVE-2021-25786: An issue was discovered in QPDF version 10.0.4, allows remote attackers to execute arbitrary code via crafted

Routine

MEDIUM 5.3DOWNGRADE

CVE-2021-25786 is a medium-severity flaw (CVSS 5.3) affecting qpdf. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in QPDF version 10.0.4, allows remote attackers to execute arbitrary code via crafted .pdf file to Pl_ASCII85Decoder::write parameter in libqpdf.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-416
Published	2023-08-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: qpdf project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-08-11 14:15 UTCPublished CVE record published
2026-06-17 03:42 UTCUpdated Record last modified

qpdf project qpdf DOWNGRADE

Affected: 10.0.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0.4

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 10.0.4 (Debian / Ubuntu)

apt-cache madison qpdf sudo apt install qpdf=<VERSION_BEFORE_10.0.4> sudo apt-mark hold qpdf

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list qpdf sudo dnf downgrade qpdf-<VERSION_BEFORE_10.0.4> sudo dnf versionlock add qpdf

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2021-25786?

qpdf: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-25786 being exploited?

CVE-2021-25786 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-2021-25786 affect?

CVE-2021-25786 affects qpdf. Severity is medium (CVSS 5.3). An issue was discovered in QPDF version 10.0.4, allows remote attackers to execute arbitrary code via crafted .pdf file to Pl_ASCII85Decoder::write parameter in libqpdf.

How urgent is CVE-2021-25786?

Priority 35/100. Public exploit reference

Related CVEs

CVE-2024-24246 MEDIUM 5.5 DOWNGRADE MITIGATE Heap Buffer Overflow vulnerability in qpdf 11.9.0 allows attackers to crash the application via the std::__sha

References

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