Jackson async Smile parser OOM/NegArray vuln (CVE-2026-104895)
CVE-2026-104895 Published on October 28, 2026

jackson-dataformat-smile: unbounded eager byte[] allocation for raw binary in the async parser allows OutOfMemoryError denial of service
The asynchronous Smile parser (NonBlockingByteArrayParser) uses a raw-binary length prefix taken from untrusted input to allocate a byte[] before the body is read, with no upper bound and no overflow check. On the raw-binary marker 0xFD, _decodeVInt() computes (value << 6) + (i & 0x3F) without the (value >>> 25) != 0 overflow guard present in the blocking SmileParser._readUnsignedVInt, and _startRawBinary then allocates the declared length immediately. A Smile feed of roughly ten bytes can therefore force an eager allocation of approximately 2 GB, producing an OutOfMemoryError on reactive or asynchronous Smile endpoints. A VInt crafted to overflow int yields a negative length and a NegativeArraySizeException, a RuntimeException that is not a JacksonException and so escapes the parser contract. Either outcome crashes the request or processing thread. This is the same class of issue as CVE-2020-28491 in the CBOR parser of this library, which was fixed with a LONGEST_NON_CHUNKED_BINARY guard; the asynchronous Smile parser never received the equivalent guard. No privileges or user interaction beyond the ability to submit data for parsing are required.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-104895 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Timeline

GHSA-h3c2-2m49-r49w published by the maintainer in FasterXML/jackson-dataformats-binary

Weakness Type

What is a Stack Exhaustion Vulnerability?

The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.

CVE-2026-104895 has been classified to as a Stack Exhaustion vulnerability or weakness.


Affected Versions

FasterXML jackson-dataformat-smile: FasterXML jackson-dataformat-smile: