CVE-2026-45799: Wire: skipGroup() missing negative-length check allows 10-byte payload to crash any Wire-decoding service

Vulnerability summary

CVE-2026-45799 is a high (CVSS 7.5) Improper Validation of Array Index vulnerability in square wire. EPSS estimates a 0.73% chance of exploitation in the next 30 days, higher than 54.3% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 17-07-2026
   PublishedVulnerability first disclosed.
2. 20-07-2026
   Last modifiedVulnerability information updated.

Description

Wire provides gRPC and protocol buffers for Android, Kotlin, Swift, and Java. Prior to 6.3.0 and 7.0.0-alpha03, ByteArrayProtoReader32.skipGroup() and ProtoReader.skipGroup() in wire-runtime do not validate that a LENGTH_DELIMITED field length is non-negative before skip(), allowing a crafted protobuf varint encoding -128 as a signed Int to make skip(-128) move the internal position negative and make the next readByte() throw ArrayIndexOutOfBoundsException instead of the documented IOException or ProtocolException, which can crash services using ProtoAdapter.decode(byte[]) on untrusted payloads. This issue is fixed in versions 6.3.0 and 7.0.0-alpha03.

• CWE-129Improper Validation of Array IndexThe product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.