CVE-2026-107705: Stack-Based Buffer Overflow in Poppler PDF Library
A security vulnerability identified as CVE-2026-107705 affects Poppler, an open-source PDF rendering and processing library. The issue is a stack-based buffer overflow in the Decrypt::revision6Hash() function, which handles password-related processing for certain encrypted PDF documents.
The vulnerability affects Poppler versions from 0.42.0 through 26.10.0, according to the published record. Under the documented conditions, a password longer than 127 bytes can overflow internal buffers while an AESV3/R6-encrypted PDF is being processed by an application using Poppler's supported interfaces.
The reported consequences include application crashes and memory corruption. Developers and system maintainers should verify their installed package status and monitor upstream and distribution security advisories for an applicable fix.
What Is CVE-2026-107705?
CVE-2026-107705 is a stack-based buffer overflow vulnerability in the Poppler PDF library.
Poppler provides PDF processing capabilities used by applications that render, inspect, or otherwise manipulate PDF documents. It can be integrated through interfaces such as libpoppler, libpoppler-glib, and the C++ API.
A stack-based buffer overflow occurs when a program writes beyond the intended capacity of a buffer allocated on the stack. Depending on the affected code and environment, this can corrupt adjacent memory, cause a crash, or produce other unintended behavior.
The published description identifies the vulnerable function as Decrypt::revision6Hash(), which is involved in processing encrypted PDF documents using the AESV3/R6 encryption path.
How Does the Vulnerability Occur?
According to the CVE description, the problem occurs when a password longer than 127 bytes is supplied through an application using the affected Poppler interfaces while processing an appropriately encrypted PDF.
The overlong password can cause the internal K1 and E buffers to overflow.
This is a specific input-handling condition. The published description does not establish that every PDF file can trigger the issue or that arbitrary code execution has been demonstrated. The documented consequences include process crashes and memory corruption.
Applications that accept PDF passwords from users or other external inputs should pay particular attention to how those values are validated before reaching a vulnerable library version.
Affected Versions and Severity
The currently published record identifies the following details:
Product: Poppler PDF processing library
Affected versions: 0.42.0 through 26.10.0
Affected function: Decrypt::revision6Hash()
Vulnerability type: Stack-based buffer overflow
CWE: CWE-121
Publication date: October 8, 2026
Reported severity: CVSS 4.0 score of 8.3 (High)
The same CVE record also contains a CVSS 3.1 assessment of 6.5 (Medium). Scores from different CVSS versions use different assessment models and should not be treated as directly interchangeable.
The impact of the flaw can also vary with the affected application, how passwords are passed to Poppler, and the permissions available to the process.
Why Is This Vulnerability Relevant?
Poppler is a library rather than a single end-user application. As a result, exposure depends on which applications and system packages include it.
A vulnerable package may be present as a dependency of a document viewer, PDF processing utility, or another application that uses Poppler internally.
Potential consequences include:
Unexpected termination of an application processing a PDF.
Memory corruption in the affected process.
Disruption to automated PDF processing workflows.
Additional security risk in applications that accept untrusted document and password inputs.
These outcomes should be understood as potential consequences of the documented weakness. The CVE description does not establish that every affected application can be exploited in the same way or that arbitrary code execution is a confirmed result.
Recommended Mitigation
1. Identify Poppler Dependencies
System administrators should check which Poppler packages are installed and determine which applications depend on them.
On Linux distributions, use the distribution's package manager and security tracker to identify the installed package version and its current vulnerability status.
Applications may bundle their own library builds, so checking the operating system package alone may not be sufficient in every environment.
2. Follow Upstream and Distribution Fixes
At the time of writing, the Debian security tracker lists its referenced Poppler packages as vulnerable or unfixed. A patch reference is associated with the upstream issue, but the availability of an applicable packaged fix can differ by distribution.
Check the official Poppler repository, the relevant distribution security tracker, and application-vendor advisories for an update explicitly identified as fixing CVE-2026-107705.
Do not assume that a release is safe simply because its version number is newer than an older vulnerable package. Confirm that the relevant correction is included.
3. Validate Password Input
Developers who use Poppler to process untrusted PDFs should review how password input is accepted and passed to the library.
As a temporary defensive measure, applications can enforce a maximum password length of 127 bytes for the affected processing path, consistent with the documented buffer limit. The implementation should be validated against the application's requirements and should not silently truncate passwords in a way that creates other security problems.
This input validation can help reduce exposure, but it should not be treated as a substitute for a verified library fix.
4. Handle Untrusted PDF Documents Carefully
Until an applicable fix has been confirmed, avoid feeding suspicious encrypted PDFs and untrusted password input into vulnerable processing environments.
For automated document processing, consider isolation, resource limits, restricted filesystem permissions, and monitoring for repeated processing failures. These controls can reduce the impact of a crash or other abnormal behavior.
5. Verify Remediation
After applying an updated package or application build, verify the installed version and the vendor's fix status.
Organizations should record which systems use the affected library and confirm that the resolved package has reached all relevant endpoints, servers, and document-processing services.
Conclusion
CVE-2026-107705 is a stack-based buffer overflow in Poppler's Decrypt::revision6Hash() function, affecting versions through 26.10.0 according to the published record.
The issue involves password handling for certain encrypted PDF documents and can lead to application crashes or memory corruption. Administrators should identify affected dependencies, follow official remediation guidance, and ensure that applications validate untrusted password input appropriately.
Because package fix status may vary between distributions, confirm the advisory for your specific environment before treating the issue as resolved.
References
Information checked on October 13, 2026. Consult current upstream and distribution advisories for confirmed fix status before updating your security documentation.
