Memory Allocation with Excessive Size Value Affecting org.bouncycastle:bcmls-jdk18on package, versions [,1.85)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published5 Aug 2026
- disclosed3 Aug 2026
- creditUnknown
Introduced: 3 Aug 2026
NewCVE-2026-12852 (opens in a new tab)How to fix?
Upgrade org.bouncycastle:bcmls-jdk18on to version 1.85 or higher.
Overview
Affected versions of this package are vulnerable to Memory Allocation with Excessive Size Value in the readOpaque() method of MLSInputStream, which decodes a varint length up to 0x3FFFFFFF (about 1 GiB) and calls readAll(size) performing new byte[size] before checking that enough bytes remain in the stream. An attacker can exhaust the JVM heap and crash the process by sending a ~6-byte MLS message whose first opaque length varint is 0xBFFFFFFF, forcing a ~1 GiB allocation per message. This requires only the ability to send raw MLS bytes to the application, since the allocation occurs before any signature or MAC verification.