Excelize: A Zip64 uncompressed-size of 2^63 panics OpenFile/OpenReader

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-107224: 0.31% estimated exploitation activity in the next 30 days; percentile 23.51 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A Zip64 uncompressed-size of 2^63 casts to a negative int64 that bypasses the unzip-size guard and reaches make([]byte, 0, negativeCap) A Zip64 uncompressed-size in the range [2^63, 2^64) casts to a negative int64 in zip.File.FileInfo().Size(), and ReadZipReader does signed arithmetic on that value, so the total-decompression guard is bypassed and the negative size reaches make([]byte, 0, size) in readFile. A 159-byte crafted file panics OpenFile and OpenReader with runtime error: makeslice: cap out of range. The guard, at lib.go:44-46 on HEAD ae2113b: FileInfo().Size() returns int64(UncompressedSize64). UncompressedSize64 is read from the Zip64 extended-information extra record in the central directory and is fully attacker controlled, so any value with the top bit set arrives as a negative int64. unzipSize then goes negative and the comparison against UnzipSizeLimit (default 1000 << 24, templates.go:193) is false no matter how many such entries the archive contains. The…

Published by the source

7 Oct 2026, 20:22 UTC

Last modified by the source

7 Oct 2026, 20:30 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-fw94-4wwp-w8pw

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-fw94-4wwp-w8pw

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# Patch Next advisory brief: CVE-2026-107224

Advisory: Excelize: A Zip64 uncompressed-size of 2^63 panics OpenFile/OpenReader
IDs: CVE-2026-107224, GHSA-fw94-4wwp-w8pw
Record: https://patchnext.com/advisories/cve-2026-107224 (revision 2, 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: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/xuri/excelize/v2 2.11.1-0.20260805032953-db93f8d89de7. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/xuri/excelize/v2: affected >= 2.1.0, < 2.11.1-0.20260805032953-db93f8d89de7; fixed in 2.11.1-0.20260805032953-db93f8d89de7

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on 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/GHSA-fw94-4wwp-w8pw (OSV record GHSA-fw94-4wwp-w8pw lists affected ranges: Go github.com/xuri/excelize/v2 >=2.1.0 <2.11.1-0.20260805032953-db93f8d89de7 (fixed))
- Verified: https://github.com/advisories/GHSA-fw94-4wwp-w8pw (GitHub-reviewed advisory GHSA-fw94-4wwp-w8pw lists affected ranges: Go github.com/xuri/excelize/v2 >=2.1.0 <2.11.1-0.20260805032953-db93f8d89de7)

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