Summary
Excelize: GetConditionalFormats indexes conditional-formatting rule sub-elements with no length or nil check
GetConditionalFormats reads sub-elements of a <cfRule> straight out of xl/worksheets/sheetN.xml and indexes them without checking length, and in one case without checking for nil. Three rule types are affected: cellIs, dataBar and colorScale. A workbook with a rule that is missing a child a real Excel file would always have panics the call.
Where it is
All three sinks are in styles.go, at the same line numbers in v2.11.0 and on master d552a7e. All three are reached from GetConditionalFormats through styles.go:3271.
styles.go:3003, in extractCondFmtCellIs:
format.Value = c.Formula[0]
The branch above it handles len(c.Formula) == 2; this one is the fallback and does not check that there is a formula at all, so a cellIs rule with no <formula> child indexes an empty slice.
styles.go:3132, in the colorScale extractor:
values := len(c.ColorScale.Cfvo)
c.ColorScale is a *xlsxColorScale and is nil when the <cfRule type="colorScale"> element has no <colorScale> child. Lines 3148 and 3153 then index Cfvo[1] and Cfvo[2] in the three-colour branch with no length check either.
styles.go:3186, :3188 and :3190, in the dataBar extractor:
format.MinType = c.DataBar.Cfvo[0].Type
...
format.BarColor = "#" + f.getThemeColor(c.DataBar.Color[0])
The guard here is c.DataBar != nil, which says nothing about the length of Cfvo or Color, so an empty <dataBar></dataBar> element reaches all three.
Who the attacker is
Anyone who can hand a spreadsheet to a service that opens it and calls GetConditionalFormats. No authentication, no user interaction beyond the service doing its normal job, and the file is small.
Reproduction
Three minimal .xlsx files were built, each a real zip with [Content_Types].xml, _rels/.rels, xl/workbook.xml, xl/_rels/workbook.xml.rels and one worksheet, opened each with the public excelize.OpenReader and called GetConditionalFormats("Sheet1"). Nothing internal is touched.
The worksheet fragment for the cellIs case, note there is no <formula> child:
<conditionalFormatting sqref="A1"><cfRule type="cellIs" operator="equal" priority="1" dxfId="0"/></conditionalFormatting>
for dataBar:
<conditionalFormatting sqref="A1"><cfRule type="dataBar" priority="1"><dataBar></dataBar></cfRule></conditionalFormatting>
and for colorScale:
<conditionalFormatting sqref="A1"><cfRule type="colorScale" priority="1"/></conditionalFormatting>
Observed against master d552a7e on go1.26.5:
cellIs panic: runtime error: index out of range [0] with length 0
styles.go:3003
styles.go:1217
styles.go:3271
dataBar panic: runtime error: index out of range [0] with length 0
styles.go:3186
styles.go:1262
styles.go:3271
colorScale panic: runtime error: invalid memory address or nil pointer dereference
styles.go:3132
styles.go:1259
styles.go:3271
One honesty note on impact. These are ordinary Go panics, not fatal errors, so a caller that wraps the call in recover survives them.
Affected versions
github.com/xuri/excelize/v2 up to and including v2.11.0, and master at d552a7e. I read the three sinks at tag v2.11.0 and at master and ran the reproducers against master.
Impact
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2026-107222 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.11.1-0.20260812075026-be7a16390fa6); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
Length-check c.Formula before line 3003 and return the rule with an empty value when there is no formula. Nil-check c.ColorScale before line 3132 and length-check ColorScale.Cfvo before indexing 1 and 2. Length-check DataBar.Cfvo and DataBar.Color alongside the existing nil check at 3186 to 3190. Skipping the malformed rule rather than erroring would keep GetConditionalFormats usable on files that are merely sloppy.
Frequently Asked Questions
- What is CVE-2026-107222? CVE-2026-107222 is a medium-severity null pointer dereference vulnerability in github.com/xuri/excelize/v2 (go), affecting versions >= 2.7.0, < 2.11.1-0.20260812075026-be7a16390fa6. It is fixed in 2.11.1-0.20260812075026-be7a16390fa6. The application dereferences a null pointer, causing a crash.
- How severe is CVE-2026-107222? CVE-2026-107222 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/xuri/excelize/v2 are affected by CVE-2026-107222? github.com/xuri/excelize/v2 (go) versions >= 2.7.0, < 2.11.1-0.20260812075026-be7a16390fa6 is affected.
- Is there a fix for CVE-2026-107222? Yes. CVE-2026-107222 is fixed in 2.11.1-0.20260812075026-be7a16390fa6. Upgrade to this version or later.
- Is CVE-2026-107222 exploitable, and should I be worried? Whether CVE-2026-107222 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-107222 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-107222? Upgrade
github.com/xuri/excelize/v2to 2.11.1-0.20260812075026-be7a16390fa6 or later.