CVE-2026-40468 in gawk
Summary
by MITRE • 07/13/2026
Integer overflow vulnerability has been found in "builtin.c" program file of gawk. This issue may lead to memory exhaustion on the hosting operating system and could be used to overwrite gawk heap metadata and objects with attacker-controlled bytes. It affects gawk in versions 5.4.0 and below.
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Analysis
by VulDB Data Team • 07/13/2026
The integer overflow vulnerability discovered in gawk's builtin.c file represents a critical security flaw that can be exploited to compromise system integrity and availability. This vulnerability specifically affects gawk versions 5.4.0 and earlier, creating a pathway for attackers to manipulate memory operations through malformed input processing. The issue stems from improper handling of integer arithmetic within the awk scripting environment, where calculations involving array sizes or loop counters can exceed maximum representable values, leading to unexpected behavior in memory allocation routines.
The technical implementation of this vulnerability involves scenarios where gawk processes input data that triggers integer overflow conditions during internal computations. When an attacker crafts malicious input that causes arithmetic operations to wrap around to smaller values, the program may allocate insufficient memory buffers or incorrectly calculate array dimensions. This misbehavior creates opportunities for heap-based memory corruption where subsequent operations can overwrite critical heap metadata structures and object contents with attacker-controlled data. The vulnerability operates at the intersection of software implementation flaws and memory management practices, making it particularly dangerous in environments where gawk processes untrusted input.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to encompass potential privilege escalation and system compromise. Memory exhaustion attacks can be leveraged to cause system instability or resource starvation, while heap metadata corruption opens pathways for more sophisticated exploitation techniques. Attackers could potentially overwrite function pointers, control structures, or other critical program data within gawk's memory space, leading to arbitrary code execution in the context of the running process. This makes the vulnerability particularly concerning for systems where gawk is used with elevated privileges or processes sensitive data from untrusted sources.
Systems utilizing gawk version 5.4.0 or earlier should immediately implement mitigations including software updates to patched versions that address the integer overflow conditions in builtin.c. Organizations should also consider implementing input validation measures and sandboxing techniques to limit potential exploitation impact, particularly when processing external data through awk scripts. The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and could potentially map to ATT&CK technique T1059.006 for script injection and execution. Network administrators should monitor for unusual memory consumption patterns or process crashes that might indicate exploitation attempts, while system hardening practices should include restricting gawk execution privileges and implementing proper input sanitization at all processing layers where awk scripts are invoked with external data sources.