High
dulwich — security advisory
Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.24.0 and prior to version 1.2.5, Dulwich's `ProcessMergeDriver` substitutes the file path (from the git tree, controllable by an attacker via a malicious branch) into the merge driver command via the `%P` placeholder and executes it with `subprocess.run(..., shell=True)`. An attacker who can cause a victim to merge an untrusted branch can achieve arbitrary command execution by crafting malicious file paths. Version 1.2.5 fixes the issue.
- Products
- dulwich
- Affected versions
- 0.11.2-1ubuntu1, 0.12.0-1, 0.12.0-1build1, 0.12.0-1build2, 0.18.2-1build1, 0.18.5-1, 0.19.11-2, 0.19.14-4ubuntu1, 0.19.15-1, 0.19.15-1build1, 0.20.15-1ubuntu1, 0.20.31-1.1, 0.20.31-1.1build1, 0.20.31-1ubuntu1, 0.21.6-1, 0.21.6-1build1, 0.21.6-1build2, 0.22.7-1, 0.24.2-2, 1.1.0-2ubuntu1, 1.1.0-3, 1.2.12-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-42563
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:03 UTC · Revision 1
Source evidence
Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.24.0 and prior to version 1.2.5, Dulwich's `ProcessMergeDriver` substitutes the file path (from the git tree, controllable by an attacker via a malicious branch) into the merge driver command via the `%P` placeholder and executes it with `subprocess.run(..., shell=True)`. An attacker who can cause a victim to merge an untrusted branch can achieve arbitrary command execution by crafting malicious file paths. Version 1.2.5 fixes the issue.
osv:UBUNTU-CVE-2026-42563
dulwich
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dulwich
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dulwich
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dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
dulwich
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dulwich
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dulwich
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Complete source record
{
"id": "2f2b0baced9bfb163d935a62fee6235e400a2a9746268b3aa333baf802e4573e",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-42563",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-42563",
"summary": "Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.24.0 and prior to version 1.2.5, Dulwich's `ProcessMergeDriver` substitutes the file path (from the git tree, controllable by an attacker via a malicious branch) into the merge driver command via the `%P` placeholder and executes it with `subprocess.run(..., shell=True)`. An attacker who can cause a victim to merge an untrusted branch can achieve arbitrary command execution by crafting malicious file paths. Version 1.2.5 fixes the issue.",
"evidence": "osv:UBUNTU-CVE-2026-42563",
"products": [
{
"name": {
"value": "dulwich",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.11.2-1ubuntu1",
"evidence": "/affected/0/versions"
},
{
"value": "0.12.0-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.12.0-1build1",
"evidence": "/affected/0/versions"
},
{
"value": "0.12.0-1build2",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "dulwich",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.18.2-1build1",
"evidence": "/affected/1/versions"
},
{
"value": "0.18.5-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "dulwich",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.19.11-2",
"evidence": "/affected/2/versions"
},
{
"value": "0.19.14-4ubuntu1",
"evidence": "/affected/2/versions"
},
{
"value": "0.19.15-1",
"evidence": "/affected/2/versions"
},
{
"value": "0.19.15-1build1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "dulwich",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.20.15-1ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "0.20.31-1ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "0.20.31-1.1",
"evidence": "/affected/3/versions"
},
{
"value": "0.20.31-1.1build1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "dulwich",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.21.6-1",
"evidence": "/affected/4/versions"
},
{
"value": "0.21.6-1build1",
"evidence": "/affected/4/versions"
},
{
"value": "0.21.6-1build2",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "dulwich",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.22.7-1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "dulwich",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.1.0-3",
"evidence": "/affected/6/versions"
},
{
"value": "1.2.12-1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "dulwich",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.22.7-1",
"evidence": "/affected/7/versions"
},
{
"value": "0.24.2-2",
"evidence": "/affected/7/versions"
},
{
"value": "1.1.0-2ubuntu1",
"evidence": "/affected/7/versions"
},
{
"value": "1.1.0-3",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-42563",
"aliases": [
"UBUNTU-CVE-2026-42563"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dulwich",
"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"0.11.2-1ubuntu1",
"0.12.0-1",
"0.12.0-1build1",
"0.12.0-1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "pypy-dulwich",
"binary_version": "0.12.0-1build2"
},
{
"binary_name": "python-dulwich",
"binary_version": "0.12.0-1build2"
},
{
"binary_name": "python3-dulwich",
"binary_version": "0.12.0-1build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dulwich",
"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"0.18.2-1build1",
"0.18.5-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "pypy-dulwich",
"binary_version": "0.18.5-1"
},
{
"binary_name": "python-dulwich",
"binary_version": "0.18.5-1"
},
{
"binary_name": "python3-dulwich",
"binary_version": "0.18.5-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dulwich",
"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"0.19.11-2",
"0.19.14-4ubuntu1",
"0.19.15-1",
"0.19.15-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "pypy-dulwich",
"binary_version": "0.19.15-1build1"
},
{
"binary_name": "python3-dulwich",
"binary_version": "0.19.15-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dulwich",
"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"0.20.15-1ubuntu1",
"0.20.31-1ubuntu1",
"0.20.31-1.1",
"0.20.31-1.1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-dulwich",
"binary_version": "0.20.31-1.1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dulwich",
"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"0.21.6-1",
"0.21.6-1build1",
"0.21.6-1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-dulwich",
"binary_version": "0.21.6-1build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
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}
]
}
],
"package": {
"name": "dulwich",
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"ecosystem": "Ubuntu:25.10"
},
"versions": [
"0.22.7-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-dulwich",
"binary_version": "0.22.7-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dulwich",
"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.1.0-3",
"1.2.12-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-dulwich",
"binary_version": "1.2.12-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dulwich",
"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"0.22.7-1",
"0.24.2-2",
"1.1.0-2ubuntu1",
"1.1.0-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42563.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-dulwich",
"binary_version": "1.1.0-3"
}
]
}
}
],
"modified": "2026-10-17T13:00:05.706936835Z",
"provider": "osv",
"upstream": [
"CVE-2026-42563"
],
"references": [
"https://ubuntu.com/security/CVE-2026-42563",
"https://www.cve.org/CVERecord?id=CVE-2026-42563",
"https://github.com/jelmer/dulwich/security/advisories/GHSA-9277-mp7x-85jf"
]
},
"related_cves": [
{
"value": "CVE-2026-42563",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 360315,
"published_at": "2026-06-10T23:16:00+00:00"
}