CVE-2020-21680 in fig2dev
Summary
by MITRE • 08/11/2021
A stack-based buffer overflow in the put_arrow() component in genpict2e.c of fig2dev 3.2.7b allows attackers to cause a denial of service (DOS) via converting a xfig file into pict2e format.
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Analysis
by VulDB Data Team • 06/26/2025
The vulnerability identified as CVE-2020-21680 represents a critical stack-based buffer overflow flaw within the fig2dev conversion utility version 3.2.7b. This issue specifically affects the put_arrow() function located in the genpict2e.c source file, which is responsible for handling the conversion of xfig files into pict2e format. The vulnerability arises during the processing of maliciously crafted xfig input files that contain malformed arrow data structures, creating a condition where the application fails to properly validate input boundaries before writing data to stack memory. The flaw enables attackers to manipulate memory layout through carefully constructed input sequences that exceed allocated buffer sizes, potentially leading to unpredictable application behavior and system instability.
The technical implementation of this vulnerability stems from insufficient bounds checking within the put_arrow() function, which processes arrow elements in xfig files during the conversion process. When the application encounters arrow data that exceeds predetermined buffer limits, the stack memory layout becomes corrupted through buffer overflow conditions. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, where the overflow occurs in stack memory allocated for local variables. The attack vector is particularly concerning because it requires no special privileges or authentication, as the vulnerability exists within a file conversion utility that processes untrusted input from external sources. The flaw demonstrates poor input validation practices and inadequate memory management within the fig2dev application's codebase.
The operational impact of CVE-2020-21680 extends beyond simple denial of service conditions to potentially enable more sophisticated attack scenarios. While the immediate effect manifests as application crashes and system instability during xfig file conversion, the underlying memory corruption could theoretically be exploited to execute arbitrary code or escalate privileges. The vulnerability affects systems running fig2dev version 3.2.7b and potentially earlier versions, making it a widespread concern for environments that rely on xfig file processing or document conversion workflows. Organizations utilizing this utility for automated document processing, graphic design workflows, or file format conversion services face significant risk exposure, as attackers could leverage this vulnerability to disrupt critical business operations or gain unauthorized access to systems through compromised conversion processes. The vulnerability aligns with ATT&CK technique T1203, which describes exploitation of software vulnerabilities for privilege escalation or system compromise through denial of service conditions.
Mitigation strategies for CVE-2020-21680 should prioritize immediate patching of affected fig2dev installations to version 3.2.7c or later, which contains the necessary code fixes for buffer overflow protection. System administrators should implement input validation measures that restrict or sanitize xfig file inputs before processing, particularly in automated workflows or web-based conversion services. Network segmentation and access controls should be enforced to limit exposure of systems running fig2dev to untrusted input sources. Additionally, organizations should establish robust monitoring procedures to detect potential exploitation attempts through unusual application behavior or crash patterns during file conversion processes. The vulnerability highlights the importance of maintaining up-to-date software libraries and implementing comprehensive input validation across all file processing components to prevent similar stack-based buffer overflow conditions from compromising system integrity and availability.