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CVE-2026-47734

CVE-2026-47734 · Dulwich has unbounded memory allocation in receive-pack from crafted thin packs

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 5.7 · Medium · EPSS 0.3% · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • dulwich

    Versions
    • >= 0.1.0, < 1.2.5: Affected

    No fix published

  • dulwich Debian:12

    Versions
    • 0.21.2-1
    • 0.21.5-1
    • 0.21.6-1
    • 0.22.5-1
    • 0.22.7-1
    • 0.22.7-2
    • 0.24.10-1
    • 0.24.2-1
    • 0.24.2-2
    • 1.0.0-1
    • 1.0.0-2
    • 1.1.0-1
    • 1.1.0-2
    • 1.1.0-3
    • 1.2.0-1
    • 1.2.1-1
    • 1.2.11-1
    • 1.2.12-1
    • 1.2.5-1
    • 1.2.7-1
    • 1.2.7-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Debian:13

    Versions
    • 0.22.7-1
    • 0.22.7-2
    • 0.24.10-1
    • 0.24.2-1
    • 0.24.2-2
    • 1.0.0-1
    • 1.0.0-2
    • 1.1.0-1
    • 1.1.0-2
    • 1.1.0-3
    • 1.2.0-1
    • 1.2.1-1
    • 1.2.11-1
    • 1.2.12-1
    • 1.2.5-1
    • 1.2.7-1
    • 1.2.7-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Debian:14

    Versions
    • 0.22.7-1
    • 0.22.7-2
    • 0.24.10-1
    • 0.24.2-1
    • 0.24.2-2
    • 1.0.0-1
    • 1.0.0-2
    • 1.1.0-1
    • 1.1.0-2
    • 1.1.0-3
    • 1.2.0-1
    • 1.2.1-1
    Affected ranges
    • ECOSYSTEM: < 1.2.5-1

    Update to 1.2.5-1

  • dulwich PyPI

    Versions
    • 0.1.0
    • 0.1.1
    • 0.10.0
    • 0.10.1a
    • 0.11.0
    • 0.11.1
    • 0.11.2
    • 0.12.0
    • 0.13.0
    • 0.14.0
    • 0.14.1
    • 0.15.0
    • 0.16.0
    • 0.16.1
    • 0.16.2
    • 0.16.3
    • 0.17.1
    • 0.17.2
    • 0.17.3
    • 0.18.0
    • 0.18.1
    • 0.18.2
    • 0.18.3
    • 0.18.4
    • 0.18.5
    • 0.18.6
    • 0.19.0
    • 0.19.1
    • 0.19.10
    • 0.19.11
    • 0.19.12
    • 0.19.13
    • 0.19.14
    • 0.19.15
    • 0.19.16
    • 0.19.2
    • 0.19.3
    • 0.19.3a0
    • 0.19.4
    • 0.19.5
    • 0.19.6
    • 0.19.7
    • 0.19.8
    • 0.19.9
    • 0.2.1
    • 0.20.0
    • 0.20.1
    • 0.20.10
    • 0.20.11
    • 0.20.12
    • 0.20.13
    • 0.20.14
    • 0.20.15
    • 0.20.17
    • 0.20.18
    • 0.20.19
    • 0.20.2
    • 0.20.20
    • 0.20.21
    • 0.20.22
    • 0.20.23
    • 0.20.24
    • 0.20.25
    • 0.20.26
    • 0.20.27
    • 0.20.28
    • 0.20.29
    • 0.20.3
    • 0.20.30
    • 0.20.31
    • 0.20.32
    • 0.20.33
    • 0.20.34
    • 0.20.35
    • 0.20.36
    • 0.20.37
    • 0.20.38
    • 0.20.39
    • 0.20.4
    • 0.20.40
    • 0.20.41
    • 0.20.42
    • 0.20.43
    • 0.20.44
    • 0.20.45
    • 0.20.46
    • 0.20.47
    • 0.20.48
    • 0.20.49
    • 0.20.5
    • 0.20.50
    • 0.20.6
    • 0.20.7
    • 0.20.8
    • 0.20.9
    • 0.21.0
    • 0.21.1
    • 0.21.2
    • 0.21.3
    • 0.21.4
    • 0.21.4.1
    • 0.21.5
    • 0.21.6
    • 0.21.7
    • 0.22.0
    • 0.22.1
    • 0.22.3
    • 0.22.4
    • 0.22.5
    • 0.22.6
    • 0.22.7
    • 0.22.8
    • 0.23.0
    • 0.23.1
    • 0.23.2
    • 0.24.0
    • 0.24.1
    • 0.24.10
    • 0.24.2
    • 0.24.3
    • 0.24.4
    • 0.24.5
    • 0.24.6
    • 0.24.7
    • 0.24.8
    • 0.24.9
    • 0.25.0
    • 0.25.1
    • 0.25.2
    • 0.3.0
    • 0.3.1
    • 0.3.2
    • 0.3.3
    • 0.4.0
    • 0.4.1
    • 0.5.0
    • 0.6.0
    • 0.6.1
    • 0.6.2
    • 0.7.0
    • 0.7.1
    • 0.8.0
    • 0.8.1
    • 0.8.2
    • 0.8.3
    • 0.8.4
    • 0.8.5
    • 0.8.6
    • 0.8.7
    • 0.9.0
    • 0.9.1
    • 0.9.2
    • 0.9.3
    • 0.9.4
    • 0.9.5
    • 0.9.6
    • 0.9.7
    • 0.9.8
    • 0.9.9
    • 1.0.0
    • 1.1.0
    • 1.2.0
    • 1.2.1
    • 1.2.2
    • 1.2.3
    • 1.2.4
    Affected ranges
    • ECOSYSTEM: ≥ 0.1.0, < 1.2.5

    Update to 1.2.5

  • dulwich Ubuntu:16.04:LTS

    Versions
    • 0.11.2-1ubuntu1
    • 0.12.0-1
    • 0.12.0-1build1
    • 0.12.0-1build2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Ubuntu:18.04:LTS

    Versions
    • 0.18.2-1build1
    • 0.18.5-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Ubuntu:20.04:LTS

    Versions
    • 0.19.11-2
    • 0.19.14-4ubuntu1
    • 0.19.15-1
    • 0.19.15-1build1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Ubuntu:22.04:LTS

    Versions
    • 0.20.15-1ubuntu1
    • 0.20.31-1ubuntu1
    • 0.20.31-1.1
    • 0.20.31-1.1build1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Ubuntu:24.04:LTS

    Versions
    • 0.21.6-1
    • 0.21.6-1build1
    • 0.21.6-1build2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Ubuntu:25.10

    Versions
    • 0.22.7-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Ubuntu:26.10

    Versions
    • 1.1.0-3
    • 1.2.12-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dulwich Ubuntu:26.04:LTS

    Versions
    • 0.22.7-1
    • 0.24.2-2
    • 1.1.0-2ubuntu1
    • 1.1.0-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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