CVE-2026-128339 json
ExcelJS through 4.4.0 Memory Exhaustion via Oversized Merged Cell Range
published 29d ago modified 17h ago also EUVD-2026-125038 , GHSA-wh3v-83h4-rwwq
Unreviewed: the maintainers' own advisory
Published by the maintainers on their GitHub repository mateocallec/exceljs-hardened. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 53%
- public exploits
- 0
- none known
Summary
ExcelJS through 4.4.0 contains a memory exhaustion vulnerability in Worksheet._parseMergeCells that allows attackers to crash applications by supplying unbounded mergeCell ranges. Attackers can craft a small workbook with a mergeCell ref like A1:XFD1048576, causing xlsx.load() to create billions of Row and Cell objects and abort the process.
Patch / fix
Is CVE-2026-128339 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- yesterday
Exploit prediction
0.69% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-14).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | exceljs-hardened | <=5.0.2 |
5.1.0 |
Affected products
- exceljs exceljs
Classification
- Weakness
-
- CWE-770 Allocation of Resources Without Limits or Throttling
References
-
github.com
/exceljs/exceljs/pull/3114
issue-tracking, patch
-
github.com
/exceljs/exceljs
product
-
github.com
/mateocallec/exceljs-hardened/security/advisories/GHSA-wh3v-83h4-rwwq
third-party-advisory, advisory
-
github.com
/exceljs/exceljs/blob/v4.4.0/lib/doc/worksheet.js#L613-L632
technical-description
-
github.com
/exceljs/exceljs/blob/v4.4.0/lib/doc/worksheet.js#L895-L901
technical-description
-
github.com
/exceljs/exceljs/issues/3107
issue-tracking
-
vulncheck.com
/advisories/exceljs-through-4.4.0-memory-exhaustion-via-oversized-merged-cell-range
third-party-advisory
Sources
- CVE List CVE-2026-128339
- NVD CVE-2026-128339
- Maintainer advisory GHSA-wh3v-83h4-rwwq
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of mateocallec/exceljs-hardened published their own advisory on GitHub. Reviewed sources take precedence over it.