CVE-2026-104016 ProtobufParser parses length-prefixed protobuf string and bytes fields by checking (_inputPtr + len) <= _inputEnd and then, on the fast path
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-104016?
CVE-2026-104016 is a high-severity vulnerability in FasterXML jackson-dataformat-protobuf, published on 27 Oct 2026.
Official description
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.
Weakness: CWE-190
Which versions are affected by CVE-2026-104016?
How do I fix CVE-2026-104016?
No fix has been published for CVE-2026-104016 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-104016 being exploited?
There is no known exploitation of CVE-2026-104016 in the wild and no public exploit code.
Sources
Also known as GHSA-c2rq-mcfv-jw29.