High
Security advisory
python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking in the difflib.IS_LINE_JUNK method. An attacker could use this flaw to cause denial of service.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2018-1061
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 06:53 UTC · Revision 1
Source evidence
python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking in the difflib.IS_LINE_JUNK method. An attacker could use this flaw to cause denial of service.
osv:CVE-2018-1061
Complete source record
{
"id": "1ffad70f4dac230bcbd375f3b355db87bb3d3389aaab42684515031a8735b016",
"url": "https://osv.dev/vulnerability/CVE-2018-1061",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2018-1061",
"summary": "python before versions 2.7.15, 3.4.9, 3.5.6rc1, 3.6.5rc1 and 3.7.0 is vulnerable to catastrophic backtracking in the difflib.IS_LINE_JUNK method. An attacker could use this flaw to cause denial of service.",
"evidence": "osv:CVE-2018-1061",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2018-1061",
"aliases": [
"CVE-2018-1061",
"PSF-2018-4"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
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{
"repo": "https://github.com/python/cpython",
"type": "GIT",
"events": [
{
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},
{
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},
{
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},
{
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},
{
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{
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{
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{
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},
{
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}
],
"database_specific": {
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{
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{
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{
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{
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},
{
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"range": [
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},
{
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}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:python:python:*:*:*:*:*:*:*:*",
"range": [
{
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},
{
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}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:python:python:3.7.0:rc1:*:*:*:*:*:*",
"range": [
{
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},
{
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}
],
"source": "CPE_STRING"
}
]
}
}
],
"versions": [
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"v3.4.9rc1",
"v3.7.0rc1",
"v2.7.15rc1",
"v3.5.5",
"v3.4.8",
"v3.5.5rc1",
"v3.4.8rc1",
"v3.6.4",
"v3.6.4rc1",
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"v3.5.4rc1",
"v3.4.7rc1",
"v3.6.2rc1",
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"v3.5.3rc1",
"v3.4.6rc1",
"v3.6.0rc1",
"v2.7.13rc1",
"v3.6.0b4",
"v3.6.0b3",
"v3.6.0b1",
"v3.6.0a3",
"v3.4.5",
"v3.5.2",
"v3.4.5rc1",
"v3.5.2rc1",
"v2.7.12rc1",
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"v2.7.5",
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"v3.3.0rc3",
"v3.3.0rc2",
"v3.3.0rc1",
"v3.3.0b2",
"v3.3.0b1",
"v3.3.0a4",
"v3.3.0a3",
"v3.3.0a2",
"v2.7.3rc1",
"v2.7.2rc1",
"v2.7",
"v3.2rc3",
"v3.2rc2",
"v3.2rc1",
"v3.2b2",
"v3.2b1",
"v2.7.1",
"v2.7.1rc1",
"v3.2a4",
"v3.2a3",
"v3.2a2",
"v3.2a1",
"v2.7rc2",
"v2.7rc1",
"v2.7b2",
"v2.7b1",
"v2.7a4",
"v2.7a3",
"v2.7a2",
"v2.7a1",
"v3.1",
"v3.1rc2",
"v3.1rc1",
"v3.1b1",
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"v3.1a1",
"v3.0rc3",
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"v2.6",
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"v3.0b3",
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"v3.0b1",
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"v2.5b3",
"v2.5b2",
"v2.5b1",
"v2.5a2",
"v2.5a1",
"v2.5a0",
"v2.4",
"v2.4c1",
"v2.4b2",
"v2.4b1",
"v2.4a3",
"v2.4a2",
"v2.4a1",
"v2.3c2",
"v2.3c1",
"v2.2a3",
"v2.1",
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"v2.1b2",
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"v2.0",
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"v2.0b2",
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"v1.5.2",
"v1.5.2c1",
"v1.5.2b2",
"v1.5.2b1",
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],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-1061.json"
}
}
],
"modified": "2026-10-24T10:30:45.873252311Z",
"provider": "osv",
"references": [
"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/46PVWY5LFP4BRPG3BVQ5QEEFYBVEXHCK/",
"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AEZ5IQT7OF7Q2NCGIVABOWYGKO7YU3NJ/",
"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JSKPGPZQNTAULHW4UH63KGOOUIDE4RRB/",
"https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbst03951en_us",
"https://access.redhat.com/errata/RHBA-2019:0327",
"https://access.redhat.com/errata/RHSA-2018:3041",
"https://access.redhat.com/errata/RHSA-2018:3505",
"https://access.redhat.com/errata/RHSA-2019:1260",
"https://access.redhat.com/errata/RHSA-2019:3725",
"https://bugs.python.org/issue32981",
"https://docs.python.org/3.5/whatsnew/changelog.html#python-3-5-6-release-candidate-1",
"https://docs.python.org/3.6/whatsnew/changelog.html#python-3-6-5-release-candidate-1",
"https://lists.debian.org/debian-lts-announce/2018/09/msg00030.html",
"https://lists.debian.org/debian-lts-announce/2018/09/msg00031.html",
"https://usn.ubuntu.com/3817-1/",
"https://usn.ubuntu.com/3817-2/",
"https://www.debian.org/security/2018/dsa-4306",
"https://www.debian.org/security/2018/dsa-4307",
"https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-1061"
],
"provider_metadata": {
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"cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*",
"cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*"
],
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{
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{
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},
{
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],
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{
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{
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]
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{
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]
},
{
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"cpe:2.3:a:python:python:3.7.0:alpha3:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.7.0:alpha4:*:*:*:*:*:*",
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},
{
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{
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},
{
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},
{
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{
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},
{
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},
{
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},
{
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{
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},
{
"introduced": "3.7.0-beta5"
},
{
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}
],
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}
]
},
{
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],
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{
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},
{
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}
],
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}
]
},
{
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],
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{
"range": [
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{
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}
],
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}
]
},
{
"cpes": [
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],
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{
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{
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},
{
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}
],
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}
]
},
{
"cpes": [
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],
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"extracted_events": [
{
"range": [
{
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},
{
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}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2018-1061",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 436223,
"published_at": "2018-06-19T12:29:00.22+00:00"
}