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High, CVSS 7.5amended

Excelize: extractPart allocates attacker-controlled, unbounded and negative-sized buffers from CFB directory entries: remote panic / OOM DoS

CVE-2026-107215GHSA-x2q3-8cjh-766f

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/360EntSecGroup-Skylar/excelize/v2

    Affected
    >= 2.3.1
    Fixed in
    no fixed version recorded

  • Go github.com/xuri/excelize/v2

    Affected
    >= 2.3.1, < 2.11.1-0.20260912113515-5f636f9dcde5
    Fixed in
    2.11.1-0.20260912113515-5f636f9dcde5

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-107215: 0.24% estimated exploitation activity in the next 30 days; percentile 15.24 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary extractPart allocates directly from the mscfb directory-entry size with no clamping (crypt.go:198, same missing bound at crypt.go:204): 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): 1. Hard crash: a version-4 CFB declaring streamSize = 0xFFFFFFFFFFFFFFFF yields entry.Size == -1 → panic: runtime error: makeslice: len out of range, which escapes Decrypt (openReaderAt converts errors, not panics, excelize.go:210-214) and kills the process. 2. Memory exhaustion: any CFB (v3 suffices)…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-x2q3-8cjh-766f

  2. Revision 2 · amended ·

    Amended from osv record GO-2026-6689

  3. Revision 1 · created ·

    Published from osv record GHSA-x2q3-8cjh-766f

Agent brief

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# Patch Next advisory brief: CVE-2026-107215

Advisory: Excelize: extractPart allocates attacker-controlled, unbounded and negative-sized buffers from CFB directory entries: remote panic / OOM DoS
IDs: CVE-2026-107215, GHSA-x2q3-8cjh-766f
Record: https://patchnext.com/advisories/cve-2026-107215 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/xuri/excelize/v2 2.11.1-0.20260912113515-5f636f9dcde5. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/360EntSecGroup-Skylar/excelize/v2: affected >= 2.3.1
- Go github.com/xuri/excelize/v2: affected >= 2.3.1, < 2.11.1-0.20260912113515-5f636f9dcde5; fixed in 2.11.1-0.20260912113515-5f636f9dcde5

## Suggested inspection (read-only)
- Go github.com/360EntSecGroup-Skylar/excelize/v2: check the installed version with your package manager.
- Go github.com/xuri/excelize/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/360EntSecGroup-Skylar/excelize/v2, github.com/xuri/excelize/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6689 (OSV record GO-2026-6689 lists affected ranges: Go github.com/360EntSecGroup-Skylar/excelize/v2 >=2.3.1; Go github.com/xuri/excelize/v2 >=0 <2.11.1-0.20260912113515-5f636f9dcde5 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-x2q3-8cjh-766f (OSV record GHSA-x2q3-8cjh-766f lists affected ranges: Go github.com/xuri/excelize/v2 >=2.3.1 <2.11.1-0.20260912113515-5f636f9dcde5 (fixed))
- Verified: https://github.com/advisories/GHSA-x2q3-8cjh-766f (GitHub-reviewed advisory GHSA-x2q3-8cjh-766f lists affected ranges: Go github.com/xuri/excelize/v2 >=2.3.1 <2.11.1-0.20260912113515-5f636f9dcde5)

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