CVE-2026-45799 is a high-severity (CVSS 7.5) CWE-129 vulnerability in com.squareup.wire:wire-runtime-jvm. O3 Security confirms whether CVE-2026-45799 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Wire: skipGroup() missing negative-length check allows 10-byte payload to crash any Wire-decoding service
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45799.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-45799 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
com.squareup.wire:wire-runtime-jvm☕com.squareup.wire:wire-runtime☕com.squareup.wire:wire-runtime☕com.squareup.wire:wire-runtime-jvmReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.squareup.wire:wire-runtime-jvm | all versions | 6.3.0 |
| ☕Maven | com.squareup.wire:wire-runtime | all versions | 6.3.0 |
| ☕Maven | com.squareup.wire:wire-runtime | ≥ 7.0.0-alpha01&&< 7.0.0-alpha03 | 7.0.0-alpha03 |
| ☕Maven | com.squareup.wire:wire-runtime-jvm | ≥ 7.0.0-alpha01&&< 7.0.0-alpha03 | 7.0.0-alpha03 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.squareup.wire:wire-runtime-jvm. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update com.squareup.wire:wire-runtime-jvm to 6.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45799 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-45799 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-45799. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-45799 in your dependencies?
O3 detects CVE-2026-45799 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.