dulwich — security advisory
Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.1.0 and prior to version 1.2.5, a client with push access could push a tiny crafted thin pack (~174 bytes) whose delta header declares a huge dest_size. When dulwich ingested it via add_thin_pack / apply_delta, it would allocate hundreds of MB of memory based on that attacker-controlled size, with no relationship to the actual bytes received. Operators running a Dulwich-based Git server that exposes git-receive-pack (i.e. accepts pushes) - for example via dulwich.server functionality, the HTTP smart server, or anything built on ReceivePackHandler - are impacted. The issue is patched in 1.2.5. add_thin_pack now accepts a max_input_size keyword (bytes; 0/None = unlimited, matching git's semantics), and ReceivePackHandler reads receive.maxInputSize from the repository config and passes it through. Wire reads are counted and a PackInputTooLarge exception is raised once the cap is exceeded - equivalent to git index-pack --max-input-size. Users should upgrade to Dulwich 1.2.5 or later and set receive.maxInputSize in their server's repository config to a sane bound for their environment. On unpatched versions, receive.maxInputSize has no effect, so it cannot be used as a workaround. Until upgrading, operators should restrict dulwich-receive-pack (push) access to trusted, authenticated clients only, or disable it entirely on servers that only need to serve fetches and/or run the serve
- 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-2026-47734
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:44 UTC · Revision 1
Source evidence
Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.1.0 and prior to version 1.2.5, a client with push access could push a tiny crafted thin pack (~174 bytes) whose delta header declares a huge dest_size. When dulwich ingested it via add_thin_pack / apply_delta, it would allocate hundreds of MB of memory based on that attacker-controlled size, with no relationship to the actual bytes received. Operators running a Dulwich-based Git server that exposes git-receive-pack (i.e. accepts pushes) - for example via dulwich.server functionality, the HTTP smart server, or anything built on ReceivePackHandler - are impacted. The issue is patched in 1.2.5. add_thin_pack now accepts a max_input_size keyword (bytes; 0/None = unlimited, matching git's semantics), and ReceivePackHandler reads receive.maxInputSize from the repository config and passes it through. Wire reads are counted and a PackInputTooLarge exception is raised once the cap is exceeded - equivalent to git index-pack --max-input-size. Users should upgrade to Dulwich 1.2.5 or later and set receive.maxInputSize in their server's repository config to a sane bound for their environment. On unpatched versions, receive.maxInputSize has no effect, so it cannot be used as a workaround. Until upgrading, operators should restrict dulwich-receive-pack (push) access to trusted, authenticated clients only, or disable it entirely on servers that only need to serve fetches and/or run the serve
osv:UBUNTU-CVE-2026-47734
dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
dulwich
Fixed versions: Not specified
Complete source record
{
"id": "348212365acc9da4195fe9ba235a31d28ea354c4a8f7bbdb3b5b6c341cf27c97",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-47734",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-47734",
"summary": "Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.1.0 and prior to version 1.2.5, a client with push access could push a tiny crafted thin pack (~174 bytes) whose delta header declares a huge dest_size. When dulwich ingested it via add_thin_pack / apply_delta, it would allocate hundreds of MB of memory based on that attacker-controlled size, with no relationship to the actual bytes received. Operators running a Dulwich-based Git server that exposes git-receive-pack (i.e. accepts pushes) - for example via dulwich.server functionality, the HTTP smart server, or anything built on ReceivePackHandler - are impacted. The issue is patched in 1.2.5. add_thin_pack now accepts a max_input_size keyword (bytes; 0/None = unlimited, matching git's semantics), and ReceivePackHandler reads receive.maxInputSize from the repository config and passes it through. Wire reads are counted and a PackInputTooLarge exception is raised once the cap is exceeded - equivalent to git index-pack --max-input-size. Users should upgrade to Dulwich 1.2.5 or later and set receive.maxInputSize in their server's repository config to a sane bound for their environment. On unpatched versions, receive.maxInputSize has no effect, so it cannot be used as a workaround. Until upgrading, operators should restrict dulwich-receive-pack (push) access to trusted, authenticated clients only, or disable it entirely on servers that only need to serve fetches and/or run the serve",
"evidence": "osv:UBUNTU-CVE-2026-47734",
"products": [
{
"name": {
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"evidence": "/affected/0/package/name"
},
"prerequisites": [],
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"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
},
{
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}
]
},
{
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},
"prerequisites": [],
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"affected_versions": [
{
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"evidence": "/affected/1/versions"
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{
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"evidence": "/affected/1/versions"
}
]
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{
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{
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"evidence": "/affected/2/versions"
},
{
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{
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}
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{
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"evidence": "/affected/3/versions"
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{
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"evidence": "/affected/3/versions"
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{
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"evidence": "/affected/3/versions"
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{
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{
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"evidence": "/affected/4/versions"
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{
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"evidence": "/affected/4/versions"
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{
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"evidence": "/affected/4/versions"
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},
{
"name": {
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"evidence": "/affected/5/package/name"
},
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"affected_versions": [
{
"value": "0.22.7-1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
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"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": {
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"evidence": "/affected/7/package/name"
},
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"affected_versions": [
{
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"evidence": "/affected/7/versions"
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{
"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": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-47734",
"aliases": [
"UBUNTU-CVE-2026-47734"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H"
},
{
"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-2026-47734.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"
}
]
}
},
{
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"package": {
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"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
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"0.18.5-1"
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"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-47734.json"
},
"ecosystem_specific": {
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"binary_version": "0.18.5-1"
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"ecosystem": "Ubuntu:20.04:LTS"
},
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"0.19.11-2",
"0.19.14-4ubuntu1",
"0.19.15-1",
"0.19.15-1build1"
],
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},
"ecosystem_specific": {
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{
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"package": {
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"purl": "pkg:deb/ubuntu/dulwich?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
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"0.20.31-1ubuntu1",
"0.20.31-1.1",
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"ecosystem": "Ubuntu:26.04:LTS"
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},
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],
"modified": "2026-10-17T12:58:57.035713846Z",
"provider": "osv",
"upstream": [
"CVE-2026-47734"
],
"references": [
"https://ubuntu.com/security/CVE-2026-47734",
"https://www.cve.org/CVERecord?id=CVE-2026-47734",
"https://github.com/jelmer/dulwich/security/advisories/GHSA-xrvj-v92f-53gj"
]
},
"related_cves": [
{
"value": "CVE-2026-47734",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359184,
"published_at": "2026-06-10T23:16:00+00:00"
}