CVE-2026-90560 in zstd-jni
Summary
by MITRE • 09/12/2026
zstd-jni versions 1.2.0 through 1.5.7-13 contain an out-of-bounds read vulnerability in the ZstdDictDecompress constructor because offset and length arguments are never validated against the dictionary array bounds. Attackers can supply arbitrary offset or length values to read memory past the end of the supplied array, potentially causing JVM termination.
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Analysis
by VulDB Data Team • 09/12/2026
The zstd-jni library serves as a Java Native Interface binding for the Zstandard compression algorithm, widely utilized in high-performance data processing pipelines across various enterprise and cloud-native applications. Versions ranging from 1.2.0 through 1.5.7-13 contain a critical memory safety flaw within the ZstdDictDecompress constructor that stems directly from insufficient input validation of native array parameters. This vulnerability represents a classic instance of improper input handling where the Java layer fails to enforce boundary checks before passing data to the underlying C implementation, creating a direct pathway for memory corruption or information disclosure attacks against systems relying on this library for dictionary-based decompression tasks.
The technical root cause lies in the absence of bounds checking for the offset and length arguments provided during the initialization of the ZstdDictDecompress object. When an application instantiates this class to prepare a compression dictionary, it typically supplies a byte array along with specific start positions and sizes defining which portion of that array constitutes valid dictionary data. The vulnerable code path accepts these parameters without verifying whether they fall within the actual limits of the supplied Java byte array. Consequently, if an attacker or malicious input source provides offset and length values that extend beyond the allocated memory region of the backing array, the native Zstandard library proceeds to read from invalid memory addresses outside the intended buffer boundaries.
This out-of-bounds read condition allows for significant operational impacts depending on the execution environment and compiler optimizations. In many Java Virtual Machine configurations, accessing memory outside the bounds of a managed object triggers an immediate segmentation fault or access violation within the native thread executing the JNI call. This results in the abrupt termination of the entire JVM process, leading to a denial-of-service condition for any service dependent on that instance. Beyond simple crashes, depending on the specific architecture and runtime environment, such memory reads may also leak sensitive information contained in adjacent heap regions or stack frames, potentially exposing cryptographic keys, session tokens, or other proprietary data structures residing near the dictionary array in memory.
From a threat modeling perspective, this vulnerability aligns with CWE-125, which defines out-of-bounds read errors resulting from failure to validate input against container limits. It also maps closely to MITRE ATT&CK technique T1083, specifically under data manipulation or exfiltration contexts where an attacker might leverage memory disclosure to gather intelligence about the target system's internal state. The risk is particularly acute in scenarios involving untrusted dictionary inputs, such as when processing user-uploaded compressed archives that utilize custom dictionaries for optimization purposes. Attackers can craft malicious payloads designed to trigger this specific constructor path with carefully calculated offset and length values to induce crashes or information leaks during routine decompression operations.
Mitigation strategies must prioritize immediate patching of the zstd-jni library to version 1.5.7-14 or later, where developers have implemented rigorous validation checks ensuring that both offset and length parameters are strictly bounded by the actual size of the provided dictionary array. For organizations unable to update immediately due to dependency constraints, defensive coding practices should be adopted at the application layer. This includes validating all input arrays for sufficient length before passing them to native methods and implementing try-catch blocks around JNI calls to gracefully handle potential runtime exceptions rather than allowing unhandled crashes to propagate through the service mesh. Additionally, enabling core dump analysis tools can help identify instances of this vulnerability in production environments by detecting abnormal process terminations associated with memory access violations during dictionary initialization phases.