CVE-2026-110747 ProtobufParser._readStringKey() reads the length prefix of a protobuf map entry's string key into an attacker-controlled int and then checks
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-110747?
CVE-2026-110747 is a high-severity vulnerability in FasterXML jackson-dataformat-protobuf, published on 28 Oct 2026.
Official description
ProtobufParser._readStringKey() reads the length prefix of a protobuf map entry's string key into an attacker-controlled int and then checks (_inputPtr + len) <= _inputEnd using signed arithmetic. For values near Integer.MAX_VALUE the addition overflows to a negative value and the check passes even when the input contains no key data. The parser then calls _finishShortText(len), which expands the text buffer to the declared length via TextBuffer.expandCurrentSegment and Arrays.copyOf, throwing OutOfMemoryError: Requested array size exceeds VM limit.
An 8-byte malformed message containing a map entry with a declared key length of 0x7FFFFFFF is sufficient. Configured StreamReadConstraints, including maxStringLength, maxNameLength, maxDocumentLength and maxNestingDepth, do not prevent the failure. Applications running with -XX:+ExitOnOutOfMemoryError terminate the JVM.
This is the same integer-overflow pattern addressed for other call sites in the remediation associated with CVE-2026-104016 and CVE-2026-104017; the map-key call site was corrected on the 3.x branches only, leaving the corresponding 2.x branches unguarded. Release lines 2.18, 2.19 and 2.20 do not contain _readStringKey() and are not affected by this vector. No privileges or user interaction beyond the ability to submit data for parsing are required. The 3.0 release line and 3.1.0-3.1.5 / 3.2.0-3.2.1 do not contain _readStringKey() and are therefore not affected; the method first appears in 3.1.6 and 3.2.2, mirroring its introduction at 2.21.6 on the 2.x side.
Weakness: CWE-190
Which versions are affected by CVE-2026-110747?
How do I fix CVE-2026-110747?
No fix has been published for CVE-2026-110747 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-110747 being exploited?
There is no known exploitation of CVE-2026-110747 in the wild and no public exploit code.
Sources
Also known as GHSA-fv7v-rrmh-4qcv.