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veraPDF Parser DoS via PostScript Type 1 Font Programs

Moderate severity GitHub Reviewed Published Jun 8, 2026 in veraPDF/veraPDF-parser • Updated Jul 29, 2026

Package

maven org.verapdf:parser (Maven)

Affected versions

<= 1.30.1
>= 1.31.1, <= 1.31.22

Patched versions

1.30.2
1.31.23

Description

Summary

Description

A PostScript-interpreter-driven Denial of Service (CWE-1325) vulnerability in veraPDF allows a remote attacker to exhaust validator memory or CPU by submitting a PDF whose Type 1 font /FontFile is a font program containing attacker-supplied PostScript. veraPDF's Type 1 font program parser dispatches every cleartext token through a hardcoded operator allow-list whose members include the unbounded array N allocation operator and the for control operator with no zero-increment guard. This affects all current versions of veraPDF-parser.

Details

The vulnerability resides in veraPDF-parser. Type 1 font program streams referenced from any Type 1 font's /FontDescriptor /FontFile are parsed by Type1FontProgram (veraPDF-parser/src/main/java/org/verapdf/pd/font/type1/Type1FontProgram.java), which extends PSParser. parseFont reads cleartext PostScript tokens until it encounters eexec (which switches into the encrypted private dictionary parser) or end-of-stream. Each non-eexec token is dispatched via toExecute, which gates execution behind a hardcoded allow-list.

The allow-list explicitly admits both ARRAY (Type1FontProgram.java:98) and FOR (Type1FontProgram.java:100). When either keyword passes the gate, operator.execute delegates straight into the generic PSOperator implementation (org.verapdf.parser.postscript.PSOperator, methods array() at PSOperator.java:536-547 and opFor() at PSOperator.java:571-592), which apply no validation:

  1. array N calls COSArray.construct(N) followed by new ArrayList<>(N) (COSArray.java:102), so the underlying Object[] is allocated up-front. Passing 2147483647 (Integer.MAX_VALUE) requests a 16 GB backing array on a 64-bit JVM.
  2. for runs for (long i = initial; i <= limit; i += increment) with no validation of increment. With increment == 0, the loop never exits.

In addition to the two shared primitives, toExecute introduces a third primitive specific to this code path: when an unknown operator is encountered, it looks the name up in userDict and recursively re-executes the value. There is no visited-set, no recursion-depth cap, and no detection of a cycle. A Type 1 font program that defines a name to itself, such as /loop { loop } def loop, recurses indefinitely on the JVM stack and throws StackOverflowError after ~16,000 frames.

The interpreter is reachable on every Type 1 font validation. GFPDType1Font's constructor unconditionally calls program.parseFont().

Type1FontProgram.parseFont only catches PostScriptException and rewraps it as IOException; it does not catch OutOfMemoryError, StackOverflowError, or wall-clock budget, so any of the three failure modes propagates out of font model construction and aborts the validation worker.

A single payload byte sequence is sufficient. The conventional %!PS-AdobeFont-1.0 header line is treated as a comment and skipped; the parser then begins consuming PostScript tokens, the very first for invocation enters the infinite loop, and the parser never reaches the eexec boundary that would normally end the cleartext section.

Impact

This impacts all current releases of the veraPDF-parser. Successful exploitation requires only that the target validate an attacker-supplied PDF; a single Type 1 font with a malicious /FontFile stream is sufficient.

References

@bdoubrov bdoubrov published to veraPDF/veraPDF-parser Jun 8, 2026
Published to the GitHub Advisory Database Jul 29, 2026
Reviewed Jul 29, 2026
Last updated Jul 29, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability Low
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

EPSS score

Weaknesses

Improperly Controlled Sequential Memory Allocation

The product manages a group of objects or resources and performs a separate memory allocation for each object, but it does not properly limit the total amount of memory that is consumed by all of the combined objects. Learn more on MITRE.

CVE ID

CVE-2026-54081

GHSA ID

GHSA-7c26-995w-6f47

Source code

Credits

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