CVE-2026-54063
HIGHCVE-2026-54063 is a high-severity (CVSS 7.5) CWE-770 vulnerability in github.com/xuri/excelize/v2. O3 Security confirms whether CVE-2026-54063 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Excelize: Unbounded Row Index Allocation in Worksheet Parser (checkSheet OOM/Panic DoS)
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-2026-54063.
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-2026-54063 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 363,908 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
github.com/xuri/excelize/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. Prior to 2.11.0, the checkSheet() function in github.com/xuri/excelize/v2 uses an attacker-controlled <row r="N"> XML attribute value directly as the length argument to make([]xlsxRow, row) without validating it against the Excel row limit (TotalRows = 1,048,576). A specially crafted XLSX file can trigger two denial-of-service variants: (A) an out-of-memory process kill when r=2147483647 forces a ~16 GB allocation attempt, and (B) a runtime panic via out-of-bounds slice indexing when r=-1. Any service that opens attacker-supplied XLSX files and calls GetCellValue is affected. No authentication is required. This issue is fixed in version 2.11.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/xuri/excelize/v2 | all versions | 2.11.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/xuri/excelize/v2. 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 github.com/xuri/excelize/v2 to 2.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54063 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-2026-54063 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-2026-54063. 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-2026-54063 in your dependencies?
O3 detects CVE-2026-54063 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.