CVE-2026-53941

## Summary An unprivileged container can block all other containers from starting on the same host by placing a crafted `/etc/ld.so.cache` file in its filesystem. When Inspektor Gadget attaches any uprobe-based gadget, it parses this file in the container startup path. A malicious cache causes ~53 seconds of CPU burn, during which Docker cannot start any other container. No special capabilities are required. ## Severity To be assessed — Availability impact, no confidentiality or integrity impact. ## Affected Versions All versions of Inspektor Gadget that support uprobe-based gadgets (trace_malloc, trace_open, trace_ssl, trace_grpc, etc.). ## Description When Inspektor Gadget attaches uprobe-based gadgets to containers, it resolves library paths by parsing the container's `/etc/ld.so.cache` file (`pkg/uprobetracer/ldcache_parser.go`). This file is fully controlled by the container. The parser has three vulnerabilities: 1. **Quadratic string building** (`pkg/uprobetracer/bytes.go:36-44`): The `readStringFromBytes` function concatenates one byte at a time (`res += string(data[i])`), which is O(n²) in Go due to string immutability. With a 16MB cache file containing large regions without null terminators, this causes massive CPU and memory churn. 2. **Insufficient entry count validation** (`pkg/uprobetracer/ldcache_parser.go:120`): The `EntryCount` field is read directly from the untrusted file. While a per-entry bounds check prevents out-of-bounds access, the loop still iterates up to `(fileSize - headerSize) / entrySize ≈ 700,000` times, calling `readStringFromBytes` on each iteration. 3. **Integer overflow in format detection** (`pkg/uprobetracer/ldcache_parser.go:174`): The `cache1Len` computation uses uint32 arithmetic (`ldCache1Size + cache1.EntryCount*ldCache1EntrySize`). With a crafted `EntryCount`, this overflows and produces a small value, causing the parser to misidentify the cache format. Combined, these cause ~53 seconds of CPU burn per container