CVE-2026-56755 in Gitea
Summary
by MITRE • 08/13/2026
Denial of Service (CPU & Memory Exhaustion) via O(N^2) String Concatenation in Debian Package Upload
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Analysis
by VulDB Data Team • 08/13/2026
This vulnerability represents a classic denial of service condition that exploits inefficient string handling mechanisms within the debian package upload process. The flaw manifests through an o n squared time complexity operation during string concatenation processes, where the computational overhead increases exponentially with input size. When maliciously crafted package uploads are processed, the system experiences dramatic performance degradation as it attempts to concatenate strings using inefficient algorithms that scale quadratically rather than linearly.
The technical implementation involves the use of suboptimal string manipulation functions within the upload handling code path. Specifically when processing package metadata or file contents, the system employs concatenation methods that require repeated memory allocations and copying operations. Each additional character or element in the input data compounds the processing time exponentially, leading to resource exhaustion patterns that can be easily triggered through carefully constructed package files. This behavior directly aligns with CWE-131, which catalogs improper handling of buffer sizes and memory allocation patterns that lead to resource consumption issues.
The operational impact extends beyond simple service disruption to encompass complete system resource exhaustion scenarios. Attackers can construct malicious packages that require excessive cpu cycles and memory allocation during upload processing, effectively consuming all available system resources and rendering the package management service unavailable to legitimate users. This creates a significant availability risk for systems relying on debian package repositories, particularly in high-throughput environments where multiple concurrent uploads occur.
The vulnerability demonstrates characteristics consistent with attack patterns found in the ATT&CK framework under the privilege escalation and resource exhaustion domains. Systems administrators must recognize that this issue can be exploited without requiring elevated privileges, making it particularly dangerous in multi-tenant environments or public package repositories. The exploitation mechanism typically involves crafting package files with carefully constructed metadata or file contents that trigger the problematic string concatenation paths within the debian packaging tools.
Mitigation strategies should focus on implementing proper input validation and sanitization mechanisms that prevent maliciously crafted data from reaching the vulnerable code paths. Code reviews should specifically target string manipulation routines to ensure they employ efficient algorithms such as StringBuilder patterns or pre-calculated buffer sizing approaches. Additionally, system administrators can implement rate limiting and resource quotas on package upload operations to prevent single requests from consuming excessive computational resources. The implementation of automated monitoring systems that detect unusual processing patterns or resource consumption spikes can also provide early warning of potential exploitation attempts, enabling proactive response measures to maintain service availability and system integrity.