msrc_cve-2021-27291
Vulnerability from csaf_microsoft
Published
2021-03-02 00:00
Modified
2024-09-11 00:00
Summary
In pygments 1.1+ fixed in 2.7.4 the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input an attacker can cause a denial of service.
Notes
Additional Resources
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
Disclaimer
The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
{
"document": {
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"title": "Additional Resources"
},
{
"category": "legal_disclaimer",
"text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
"title": "Disclaimer"
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"publisher": {
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"name": "Microsoft Security Response Center",
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"references": [
{
"category": "self",
"summary": "CVE-2021-27291 In pygments 1.1+ fixed in 2.7.4 the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input an attacker can cause a denial of service. - VEX",
"url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-27291.json"
},
{
"category": "external",
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"url": "https://support.microsoft.com/lifecycle"
},
{
"category": "external",
"summary": "Common Vulnerability Scoring System",
"url": "https://www.first.org/cvss"
}
],
"title": "In pygments 1.1+ fixed in 2.7.4 the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input an attacker can cause a denial of service.",
"tracking": {
"current_release_date": "2024-09-11T00:00:00.000Z",
"generator": {
"date": "2025-10-19T21:50:22.158Z",
"engine": {
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"version": "1.0"
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},
"id": "msrc_CVE-2021-27291",
"initial_release_date": "2021-03-02T00:00:00.000Z",
"revision_history": [
{
"date": "2021-03-24T00:00:00.000Z",
"legacy_version": "1",
"number": "1",
"summary": "Information published."
},
{
"date": "2021-12-16T00:00:00.000Z",
"legacy_version": "1.1",
"number": "2",
"summary": "Added python-pygments to CBL-Mariner 2.0"
},
{
"date": "2024-08-29T00:00:00.000Z",
"legacy_version": "1.2",
"number": "3",
"summary": "Information published."
},
{
"date": "2024-08-30T00:00:00.000Z",
"legacy_version": "1.3",
"number": "4",
"summary": "Information published."
},
{
"date": "2024-08-31T00:00:00.000Z",
"legacy_version": "1.4",
"number": "5",
"summary": "Information published."
},
{
"date": "2024-09-01T00:00:00.000Z",
"legacy_version": "1.5",
"number": "6",
"summary": "Information published."
},
{
"date": "2024-09-02T00:00:00.000Z",
"legacy_version": "1.6",
"number": "7",
"summary": "Information published."
},
{
"date": "2024-09-03T00:00:00.000Z",
"legacy_version": "1.7",
"number": "8",
"summary": "Information published."
},
{
"date": "2024-09-05T00:00:00.000Z",
"legacy_version": "1.8",
"number": "9",
"summary": "Information published."
},
{
"date": "2024-09-06T00:00:00.000Z",
"legacy_version": "1.9",
"number": "10",
"summary": "Information published."
},
{
"date": "2024-09-07T00:00:00.000Z",
"legacy_version": "2",
"number": "11",
"summary": "Information published."
},
{
"date": "2024-09-08T00:00:00.000Z",
"legacy_version": "2.1",
"number": "12",
"summary": "Information published."
},
{
"date": "2024-09-11T00:00:00.000Z",
"legacy_version": "2.2",
"number": "13",
"summary": "Information published."
}
],
"status": "final",
"version": "13"
}
},
"product_tree": {
"branches": [
{
"branches": [
{
"branches": [
{
"category": "product_version",
"name": "3.0",
"product": {
"name": "Azure Linux 3.0",
"product_id": "17084"
}
}
],
"category": "product_name",
"name": "Azure Linux"
},
{
"branches": [
{
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"name": "\u003cazl3 python-pygments 2.7.4-1",
"product": {
"name": "\u003cazl3 python-pygments 2.7.4-1",
"product_id": "2"
}
},
{
"category": "product_version",
"name": "azl3 python-pygments 2.7.4-1",
"product": {
"name": "azl3 python-pygments 2.7.4-1",
"product_id": "16993"
}
},
{
"category": "product_version_range",
"name": "\u003cazl3 python-pygments 2.5.2-1",
"product": {
"name": "\u003cazl3 python-pygments 2.5.2-1",
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},
{
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"relationships": [
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"name": "\u003cazl3 python-pygments 2.7.4-1 as a component of Azure Linux 3.0",
"product_id": "17084-2"
},
"product_reference": "2",
"relates_to_product_reference": "17084"
},
{
"category": "default_component_of",
"full_product_name": {
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{
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},
"vulnerabilities": [
{
"cve": "CVE-2021-27291",
"cwe": {
"id": "CWE-1333",
"name": "Inefficient Regular Expression Complexity"
},
"notes": [
{
"category": "general",
"text": "mitre",
"title": "Assigning CNA"
}
],
"product_status": {
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"16993-17084",
"19947-17084"
],
"known_affected": [
"17084-2",
"17084-1"
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},
"references": [
{
"category": "self",
"summary": "CVE-2021-27291 In pygments 1.1+ fixed in 2.7.4 the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input an attacker can cause a denial of service. - VEX",
"url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-27291.json"
}
],
"remediations": [
{
"category": "vendor_fix",
"date": "2021-03-24T00:00:00.000Z",
"details": "2.7.4-1:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
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"url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
}
],
"scores": [
{
"cvss_v3": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"environmentalsScore": 0.0,
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"temporalScore": 7.5,
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"products": [
"17084-2",
"17084-1"
]
}
],
"title": "In pygments 1.1+ fixed in 2.7.4 the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input an attacker can cause a denial of service."
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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