NVD / CVE Program· CNA mitre

CVE-2021-25786: An issue was discovered in QPDF version 10.0.4, allows remote attackers to execute arbitrary code via crafted .pdf file to Pl_ASCII85Decoder

Noroxi assessment

Priority: Monitor (action score 21/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.53% (FIRST EPSS).
Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
Fixed version: qpdf (Debian:10) 8.4.0-2+deb10u1; qpdf (Debian:12) 10.1.0-1.

Low priority for now. Upgrade to qpdf (Debian:10) 8.4.0-2+deb10u1; qpdf (Debian:12) 10.1.0-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.3 · v3.1—No exploit Fix available

Published: Aug 11, 2023
Updated: Jun 16, 2026
EPSS: 0.5% · 45th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 21 / 40 · 5.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.5%

CISA SSVC decision

Exploitation: proof of concept
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
qpdf project	qpdf	cpe:2.3:a:qpdf_project:qpdf

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

qpdf project qpdf10.0.4

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:10	qpdf	before 8.4.0-2+deb10u1	8.4.0-2+deb10u1
Debian:12	qpdf	before 10.1.0-1	10.1.0-1

Same product

qpdf project: all records

Other highest-scoring records for the same primary product.

CVE-2018-9918libqpdf.a in QPDF through 8.0.2 mishandles certain "expected dictionary key but found non-name object" cases, allowing remote attackers to c
32Monitor
CVE-2017-12595The tokenizer in QPDF 6.0.0 and 7.0.b1 is recursive for arrays and dictionaries, which allows remote attackers to cause a denial of service
32Monitor
CVE-2022-34503QPDF v8.4.2 was discovered to contain a heap buffer overflow via the function QPDF::processXRefStream.
26Monitor

Published before and after this one in the same product

← EarlierCVE-2018-18020Oct 6, 2018 · In QPDF 8.2.1, in libqpdf/QPDFWriter.cc, QPDFWriter::unparseObject and QPDFWriter::unparseChild have recursive calls for a long time, which
13Monitor
← EarlierCVE-2021-36978Jul 20, 2021 · QPDF 9.x through 9.1.1 and 10.x through 10.0.4 has a heap-based buffer overflow in Pl_ASCII85Decoder::write (called from Pl_AES_PDF::flush a
22Monitor
Later →CVE-2024-24246Feb 29, 2024 · Heap Buffer Overflow vulnerability in qpdf 11.9.0 allows attackers to crash the application via the std::__shared_count() function at /bits/
22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
debian:qpdf	10.1.0-1 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Someone with local access to the system can trigger it.
No account or password is required.
A user must open a link or visit a page.
No special conditions are required; it is repeatable.

If successful

Confidentiality: low · data can be read
Integrity: low · data or configuration can be modified
Availability: low · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality impact: Low
Integrity impact: Low
Availability impact: Low

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:48 PM UTC

For records you follow, these changes also arrive as notifications. →

References

lists.debian.org/debian-lts-announce/2023/08/msg00037.html

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records