CVE-2026-78207

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Source
https://cve.org/CVERecord?id=CVE-2026-78207
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-78207.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-78207
Aliases
  • GHSA-qwr4-7h29-chpf
Published
2026-08-24T00:30:47.125Z
Modified
2026-08-30T03:48:21.739501993Z
Severity
  • 9.3 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N CVSS Calculator
Summary
exceljs through 4.4.0 Prototype Pollution via deepMerge Reached From Note Serialization
Details

exceljs through 4.4.0 contains a prototype pollution vulnerability in the deepMerge helper that fails to reject proto, constructor, or prototype keys when merging note objects. Attackers can assign parsed JSON with a malicious proto property to cell notes, modifying Object.prototype and affecting all plain objects created in the process.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/78xxx/CVE-2026-78207.json",
    "cwe_ids": [
        "CWE-1321"
    ],
    "cna_assigner": "VulnCheck"
}
References

Affected packages

Git / github.com/exceljs/exceljs

Affected ranges

Type
GIT
Repo
https://github.com/exceljs/exceljs
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Last affected
ac96f9a61e9799c7776bd940f05c4a51d7200209
Database specific
Show details 
{
    "source": "AFFECTED_FIELD",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "last_affected": "4.4.0"
        }
    ]
}
Type
GIT
Repo
https://github.com/mateocallec/exceljs-hardened
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
37149551343c6305aa8aca4f43567c1091102287
Database specific
Show details 
{
    "source": "DESCRIPTION",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "5.0.0"
        }
    ]
}

Affected versions

0.*
0.0.1
0.0.2
0.0.3
0.0.4
0.0.5
0.0.6
0.0.7
0.0.8
0.0.9
0.1.0
0.1.1
0.1.10
0.1.11
0.1.2
0.1.3
0.1.4
0.1.5
0.1.6
0.1.7
0.1.8
0.1.9
0.2.0
0.2.1
0.2.10
0.2.11
0.2.12
0.2.15
0.2.16
0.2.17
0.2.18
0.2.19
0.2.2
0.2.20
0.2.21
0.2.22
0.2.23
0.2.24
0.2.26
0.2.27
0.2.28
0.2.29
0.2.3
0.2.30
0.2.31
0.2.33
0.2.34
0.2.35
0.2.36
0.2.8
v0.*
v0.0.1
v0.0.2
v0.0.3
v0.0.4
v0.0.5
v0.0.6
v0.0.7
v0.0.8
v0.0.9
v0.1.0
v0.1.1
v0.1.10
v0.1.11
v0.1.2
v0.1.3
v0.1.4
v0.1.5
v0.1.6
v0.1.7
v0.1.8
v0.1.9
v0.2.0
v0.2.1
v0.2.10
v0.2.11
v0.2.12
v0.2.15
v0.2.16
v0.2.17
v0.2.18
v0.2.19
v0.2.2
v0.2.20
v0.2.21
v0.2.22
v0.2.23
v0.2.24
v0.2.26
v0.2.27
v0.2.28
v0.2.29
v0.2.3
v0.2.30
v0.2.31
v0.2.33
v0.2.34
v0.2.35
v0.2.36
v0.2.8
v0.4.10
v0.4.11
v0.4.12
v0.4.13
v0.4.14
v0.4.9
v0.5.0
v0.5.1
v0.6.0
v0.6.2
v0.7.0
v0.7.1
v0.8.0
v0.8.1
v0.8.2
v0.8.3
v0.8.4
v0.8.5
v0.9.0
v0.9.1
v1.*
v1.0.0
v1.0.1
v1.0.2
v1.1.0
v1.1.1
v1.1.2
v1.1.3
v1.10.0
v1.11.0
v1.12.0
v1.12.1
v1.12.2
v1.13.0
v1.14.0
v1.15.0
v1.2.0
v1.2.1
v1.3.0
v1.4.0
v1.4.1
v1.4.10
v1.4.11
v1.4.12
v1.4.13
v1.4.2
v1.4.3
v1.4.4
v1.4.5
v1.4.6
v1.4.7
v1.4.8
v1.4.9
v1.5.0
v1.5.1
v1.6.0
v1.6.1
v1.6.2
v1.6.3
v1.7.0
v1.8.0
v1.9.0
v1.9.1
v2.*
v2.0.0
v2.0.1
v3.*
v3.0.0
v3.1.0
v3.10.0
v3.2.0
v3.3.0
v3.3.1
v3.4.0
v3.5.0
v3.7.0
v3.8.0
v3.8.1
v3.8.2
v3.9.0
v4.*
v4.0.0
v4.0.1
v4.1.0
v4.1.1
v4.2.0
v4.2.1
v4.3.0
v4.4.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-78207.json"