Exploitation evidence
Known exploited · CISA KEV listed
Added 2021-11-03. Ransomware campaign use: Unknown.
CISA required action: Apply updates per vendor instructions.
CISA due date: 2021-11-17. This is the catalog’s deadline, not an assessment of your organization’s exposure.
KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗Reported products and versions
Apple / iOS and iPadOS
Default status: Not specified
- affected: unspecified to < 14.4 (custom)
Apple / iOS
Default status: Not specified
- affected: unspecified to < 12.5 (custom)
Apple / watchOS
Default status: Not specified
- affected: unspecified to < 7.3 (custom)
Fixes and workarounds
No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.
Sources and related reporting
Observed change timeline
History begins when Egret first downloads each source. It is not the complete upstream CVE history.
12 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-12",
"epss": 0.07082,
"percentile": 0.94309
}10 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-10",
"epss": 0.07082,
"percentile": 0.94272
}09 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-09",
"epss": 0.07082,
"percentile": 0.94265
}08 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-08",
"epss": 0.07082,
"percentile": 0.94262
}07 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-07",
"epss": 0.07082,
"percentile": 0.94259
}06 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-06",
"epss": 0.07082,
"percentile": 0.94251
}06 Nov 2026, 00:20 Jerusalem · CVE Program record changed
Stored CNA snapshot at this observation.
{
"containers": {
"adp": [
{
"providerMetadata": {
"dateUpdated": "2024-08-03T16:25:06.324Z",
"orgId": "af854a3a-2127-422b-91ae-364da2661108",
"shortName": "CVE"
},
"references": [
{
"tags": [
"x_refsource_MISC",
"x_transferred"
],
"url": "https://support.apple.com/en-us/HT212256"
},
{
"tags": [
"x_refsource_MISC",
"x_transferred"
],
"url": "https://support.apple.com/en-us/HT212257"
},
{
"tags": [
"x_refsource_MISC",
"x_transferred"
],
"url": "https://support.apple.com/en-us/HT212258"
}
],
"title": "CVE Program Container"
},
{
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
}
},
{
"other": {
"content": {
"id": "CVE-2021-1879",
"options": [
{
"Exploitation": "active"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2025-01-29T17:31:41.503370Z",
"version": "2.0.3"
},
"type": "ssvc"
}
},
{
"other": {
"content": {
"dateAdded": "2021-11-03",
"reference": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1879"
},
"type": "kev"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-79",
"description": "CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2025-10-21T23:25:49.688Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"government-resource"
],
"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1879"
}
],
"timeline": [
{
"lang": "en",
"time": "2021-11-03T00:00:00.000Z",
"value": "CVE-2021-1879 added to CISA KEV"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "iOS and iPadOS",
"vendor": "Apple",
"versions": [
{
"lessThan": "14.4",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
},
{
"product": "iOS",
"vendor": "Apple",
"versions": [
{
"lessThan": "12.5",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
},
{
"product": "watchOS",
"vendor": "Apple",
"versions": [
{
"lessThan": "7.3",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited.."
}
],
"problemTypes": [
{
"descriptions": [
{
"description": "Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited.",
"lang": "en",
"type": "text"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2021-04-02T18:07:52.000Z",
"orgId": "286789f9-fbc2-4510-9f9a-43facdede74c",
"shortName": "apple"
},
"references": [
{
"tags": [
"x_refsource_MISC"
],
"url": "https://support.apple.com/en-us/HT212256"
},
{
"tags": [
"x_refsource_MISC"
],
"url": "https://support.apple.com/en-us/HT212257"
},
{
"tags": [
"x_refsource_MISC"
],
"url": "https://support.apple.com/en-us/HT212258"
}
],
"x_legacyV4Record": {
"CVE_data_meta": {
"ASSIGNER": "product-security@apple.com",
"ID": "CVE-2021-1879",
"STATE": "PUBLIC"
},
"affects": {
"vendor": {
"vendor_data": [
{
"product": {
"product_data": [
{
"product_name": "iOS and iPadOS",
"version": {
"version_data": [
{
"version_affected": "<",
"version_value": "14.4"
}
]
}
},
{
"product_name": "iOS",
"version": {
"version_data": [
{
"version_affected": "<",
"version_value": "12.5"
}
]
}
},
{
"product_name": "watchOS",
"version": {
"version_data": [
{
"version_affected": "<",
"version_value": "7.3"
}
]
}
}
]
},
"vendor_name": "Apple"
}
]
}
},
"data_format": "MITRE",
"data_type": "CVE",
"data_version": "4.0",
"description": {
"description_data": [
{
"lang": "eng",
"value": "This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited.."
}
]
},
"problemtype": {
"problemtype_data": [
{
"description": [
{
"lang": "eng",
"value": "Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited."
}
]
}
]
},
"references": {
"reference_data": [
{
"name": "https://support.apple.com/en-us/HT212256",
"refsource": "MISC",
"url": "https://support.apple.com/en-us/HT212256"
},
{
"name": "https://support.apple.com/en-us/HT212257",
"refsource": "MISC",
"url": "https://support.apple.com/en-us/HT212257"
},
{
"name": "https://support.apple.com/en-us/HT212258",
"refsource": "MISC",
"url": "https://support.apple.com/en-us/HT212258"
}
]
}
}
}
},
"cveMetadata": {
"assignerOrgId": "286789f9-fbc2-4510-9f9a-43facdede74c",
"assignerShortName": "apple",
"cveId": "CVE-2021-1879",
"datePublished": "2021-04-02T18:07:52.000Z",
"dateReserved": "2020-12-08T00:00:00.000Z",
"dateUpdated": "2025-10-21T23:25:49.688Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1"
}05 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-05",
"epss": 0.07082,
"percentile": 0.94246
}04 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-04",
"epss": 0.07082,
"percentile": 0.94242
}03 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-03",
"epss": 0.07082,
"percentile": 0.94232
}03 Nov 2026, 02:22 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-02",
"epss": 0.07082,
"percentile": 0.94224
}03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed
Stored KEV snapshot at this observation.
{
"cveID": "CVE-2021-1879",
"cwes": [
"CWE-79"
],
"dateAdded": "2021-11-03",
"dueDate": "2021-11-17",
"forensicTriage": "No",
"knownRansomwareCampaignUse": "Unknown",
"notes": "https://nvd.nist.gov/vuln/detail/CVE-2021-1879",
"product": "iOS, iPadOS, and watchOS",
"requiredAction": "Apply updates per vendor instructions.",
"shortDescription": "Apple iOS, iPadOS, and watchOS WebKit contain an unspecified vulnerability that allows for universal cross-site scripting (XSS) when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.",
"vendorProject": "Apple",
"vulnerabilityName": "Apple iOS, iPadOS, and watchOS WebKit Cross-Site Scripting (XSS) Vulnerability"
}