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Fencer Intel
medium 5.7

CVE-2026-47734 json

Dulwich has unbounded memory allocation in receive-pack from crafted thin packs

published 5mo ago modified 3mo ago also EUVD-2026-36193 , GHSA-xrvj-v92f-53gj , PYSEC-2026-2466

cvss
5.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

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 server under an OS-level memory limit (e.g. ulimit, cgroups/MemoryMax, or a container memory limit) so a malicious push is killed rather than taking down the host.

Patch / fix

  • pypi dulwich 1.2.5
  • dulwich_project dulwich 1.2.5
  • dulwich Debian 14 1.2.5-1

debian advisories DEBIAN-CVE-2026-47734

  • python-dulwich SLE Module for Public Cloud 12 0.18.5-4.6.1
  • python3-dulwich SLE Module for Basesystem 15 SP7 0.20.24-150400.8.1

suse advisories SUSE-SU-2026:3117-1SUSE-SU-2026:2984-1

Is CVE-2026-47734 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-47734 updated cvss 6.5

dulwich: Dulwich: Denial of Service via crafted Git thin pack

  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/controller-rhel9, ansible-automation-platform-27/controller-rhel9, ansible-automation-platform-26/eda-controller-rhel9, ansible-automation-platform-27/eda-controller-rhel9, ansible-automation-platform-26/lightspeed-chatbot-rhel9 Red Hat Enterprise Linux 7 resource-agents, resource-agents-gcp, resource-agents-sap, sap-cluster-connector, resource-agents-aliyun, resource-agents-sap-hana, +1 more Red Hat Enterprise Linux 8 resource-agents, resource-agents-gcp, resource-agents-paf, resource-agents-aliyun Red Hat OpenShift AI (RHOAI) rhoai/odh-kserve-agent-rhel9, rhoai/odh-kserve-router-rhel9, rhoai/odh-kserve-controller-rhel9, rhoai/odh-kserve-autogluon-server-rhel9, rhoai/odh-kserve-storage-initializer-rhel9 Red Hat OpenShift Container Platform 4 python-dulwich Red Hat Satellite 6 python-dulwich
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5mo ago

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 5.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
GitHub 3.1 5.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
OSV 3.1 5.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi dulwich
>=0.1.0, <1.2.5
1.2.5

Affected products

  • jelmer dulwich

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-789 Memory Allocation with Excessive Size Value

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of jelmer/dulwich published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.