Vulnerability in github.com/xuri/excelize/v2 (CVE-2026-107215)
Summary
Vulnerability in github.com/xuri/excelize/v2 (CVE-2026-107215). Risk of unauthorized operations or information disclosure. Exploitable via extractPart. Mitigation: upgrade to 2.11.1-0.20260912113515-5f636f9dcde5 or later.
Original description
The description as published by the source.
Summary
extractPart allocates directly from the mscfb directory-entry size with no clamping (crypt.go:198, same missing bound at crypt.go:204):
buf := make([]byte, entry.Size)
entry.Size is the raw streamSize field from the attacker-controlled CFB directory entry (mscfb v1.0.8 fixFile, file.go:109-120: full uint64 → int64 for major version 4, low uint32 for v3). mscfb only detects short sector chains later, inside File.Read (file.go:485-489 "emergency brake") — i.e. after the allocation. The zip path already enforces UnzipSizeLimit, and the KDF path bounds work with maxSpinCount; this path consults no limit at all.
Details
Two consequences, both execution-confirmed against pristine master (ecd99d761fe0, 2026-09-08):
- Hard crash: a version-4 CFB declaring
streamSize = 0xFFFFFFFFFFFFFFFFyieldsentry.Size == -1→panic: runtime error: makeslice: len out of range, which escapesDecrypt(openReaderAtconverts errors, not panics,excelize.go:210-214) and kills the process. - Memory exhaustion: any CFB (v3 suffices) declaring
streamSizeup to0xFFFFFFFFforces up to 4 GiB of zeroed allocation from a ~12 KB file — an amplification factor of ~350,000×, trivially repeated per request in memory-limited deployments.
Call path: OpenFile/OpenReader/OpenBytes → openReaderAt (excelize.go:208-215, OLE magic sniff) → Decrypt (crypt.go:145-150) → extractPart (crypt.go:198).
PoC
A standalone…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-107215 has been found in github.com/xuri/excelize/v2.
Attackers can target a specific entry point like extractPart over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade github.com/xuri/excelize/v2 to 2.11.1-0.20260912113515-5f636f9dcde5 or later.
If unsure, ask your IT team or search "github.com/xuri/excelize/v2 CVE-2026-107215" on the vendor's site.
CVE-2026-107215 (github.com/xuri/excelize/v2) — CWE-789 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: extractPart / entry.Size / streamSize / fixFile
Patched: 2.11.1-0.20260912113515-5f636f9dcde5 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-789) exists in github.com/xuri/excelize/v2. Attackers reach the vulnerable code path via extractPart without authentication.
Check the vendor advisory for the affected versions of github.com/xuri/excelize/v2. Attack surface: extractPart / entry.Size / streamSize / fixFile.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 2.11.1-0.20260912113515-5f636f9dcde5.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/xuri/excelize/v2' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/xuri/excelize/v2' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/xuri/excelize/v2を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/xuri/excelize/v2 to 2.11.1-0.20260912113515-5f636f9dcde5ステージング環境で 2.11.1-0.20260912113515-5f636f9dcde5 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com