CVE-2026-128338
What it is
exceljs through 4.4.0 contains a memory exhaustion vulnerability that allows attackers to crash applications by supplying a worksheet col element with an unbounded max attribute. Attackers can craft a small workbook with a huge max value, causing xlsx.load() to allocate hundreds of millions of Column objects and abort the process with an uncatchable heap out-of-memory error.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 0.6% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.6% in the next 30 days (EPSS).
- Severity: 8.7 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.6% · EPSS, next 30 days
- Weakness
- CWE-770 · Allocation without limits
- Record status
- Awaiting Analysis
Attack profile CVSS 4.0 · 8.7
- Attack vector
- Network
- Complexity
- Low
- Attack requirements
- None
- Privileges needed
- None
- User interaction
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
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
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-128338.md and follow it. Check whether this project is affected by CVE-2026-128338. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
References
- https://github.com/exceljs/exceljs
- https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/column.js#L307-L316
- https://github.com/exceljs/exceljs/blob/v4.4.0/lib/xlsx/xform/sheet/col-xform.js#L43-L47
- https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-w57r-3mm6-w6g7
- https://www.vulncheck.com/advisories/exceljs-through-4.4.0-memory-exhaustion-via-unbounded-worksheet-column-range