jackson-dataformat-protobuf: signed integer overflow in string-length paths allows unbounded array allocation and OutOfMemoryError

Overview

ProtobufParser parses length-prefixed protobuf string and bytes fields by checking (_inputPtr + len) <= _inputEnd and then, on the fast path, calling _finishShortText(len). Both use 32-bit signed integer arithmetic. When an attacker supplies a varint decoding to a length near Integer.MAX_VALUE, _inputPtr + len overflows to a negative value, the bounds check passes, and _finishShortText(len) reaches TextBuffer.expandCurrentSegment(len), which performs Arrays.copyOf with no cap and throws OutOfMemoryError: Requested array size exceeds VM limit.

The JVM refuses arrays larger than Integer.MAX_VALUE - 8 before consulting available heap, so -Xmx tuning does not mitigate the issue. StreamReadConstraints.maxStringLength and maxDocumentLength do not gate this path: a 33-byte payload is far below any document-length cap and the string-length check does not fire before the allocation. This was confirmed empirically against shipping artifacts with maxStringLength, maxDocumentLength and maxNestingDepth all configured.

A February 2026 hardening commit added the equivalent overflow guard to the packed-array-length and message-length paths but left the string-length call sites unguarded. No privileges or user interaction beyond the ability to submit data for parsing are required.

Affected

• com.fasterxml.jackson.dataformat:jackson-dataformat-protobuf >= 2.6.0 < 2.18.12
• com.fasterxml.jackson.dataformat:jackson-dataformat-protobuf >= 2.19.0 < 2.21.8
• com.fasterxml.jackson.dataformat:jackson-dataformat-protobuf >= 2.22.0 < 2.22.4
• tools.jackson.dataformat:jackson-dataformat-protobuf >= 3.0.0 < 3.1.8
• tools.jackson.dataformat:jackson-dataformat-protobuf >= 3.2.0 < 3.2.4

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.