CVE-2026-87824
Description
A flaw was found in zstd-jni. Attackers can exploit this by supplying oversized per-sample lengths to the Zstd.trainFromBufferDirect function, which fails to validate the samples buffer capacity. This allows for reading past buffer boundaries, leading to out-of-bounds memory access and ultimately causing the Java Virtual Machine (JVM) to terminate, resulting in a Denial of Service (DoS).
Statement
Red Hat has determined that CVE-2026-87824 affects Red Hat products that include the zstd-jni library in a vulnerable version. The vulnerability can allow a remote attacker to terminate the Java Virtual Machine by supplying crafted sample lengths to the dictionary-training function.
Mitigation
No complete workaround is currently available. As a temporary measure, applications using Zstd.trainFromBufferDirect() should validate that all sample lengths are non-negative and that their total does not exceed the capacity of the samples buffer before calling the function. Avoid passing attacker-controlled sample length arrays to this function until an update is available. Upgrade to a Red Hat product release containing zstd-jni 1.5.7-14 or later when available.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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