Dulwich is a pure-Python implementation of the Git file formats and protocols. Versions starting with 0.10.0 and prior to 1.2.5 have an arbitrary file write leading to remote code execution when cloning or checking out a malicious Git repository on Windows. Dulwich's path-element validator accepted tree entries whose filenames contained bytes that Windows interprets as structural path syntax. Contributing configuration bugs made matters worse. The core.protectNTFS and core.protectHFS settings were looked up under a wrong option name and so user-set values were silently ignored, and core.protectNTFS only defaulted to true on Windows (Git upstream has defaulted it to true everywhere since CVE-2019-1353). Both have been corrected. Anyone who clones, fetches, or checks out an untrusted repository with Dulwich on Windows - either through the Dulwich CLI, porcelain.clone, or any downstream tool built on Dulwich - is impacted. POSIX clones are not directly exploitable (on POSIX \ is a literal filename byte), but a POSIX user can unknowingly propagate a malicious tree to Windows consumers via push or re-publication. This issue is fixed in Dulwich 1.2.5. Users should upgrade to 1.2.5 or later. There is no effective pre-patch workaround. On affected versions the core.protectNTFS configuration key was silently ignored, so setting it to true does not mitigate the issue. Users who cannot upgrade should avoid cloning, fetching, or checking out untrusted repositories with Dulwich on Windows. After upgrading the NTFS validator is on by default on every platform, so no additional configuration is required.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - Dulwich is a pure-Python implementation of the Git file formats and protocols. Versions starting with
    0.10.0 and prior to 1.2.5 have an arbitrary file write leading to remote code execution when cloning or
    checking out a malicious Git repository on Windows. Dulwich's path-element validator accepted tree entries
    whose filenames contained bytes that Windows interprets as structural path syntax. Contributing
    configuration bugs made matters worse. The core.protectNTFS and core.protectHFS settings were looked up
    under a wrong option name and so user-set values were silently ignored, and core.protectNTFS only
    defaulted to true on Windows (Git upstream has defaulted it to true everywhere since CVE-2019-1353). Both
    have been corrected. Anyone who clones, fetches, or checks out an untrusted repository with Dulwich on
    Windows - either through the Dulwich CLI, porcelain.clone, or any downstream tool built on Dulwich - is
    impacted. POSIX clones are not directly exploitable (on POSIX \ is a literal filename byte), but a POSIX
    user can unknowingly propagate a malicious tree to Windows consumers via push or re-publication. This
    issue is fixed in Dulwich 1.2.5. Users should upgrade to 1.2.5 or later. There is no effective pre-patch
    workaround. On affected versions the core.protectNTFS configuration key was silently ignored, so setting
    it to true does not mitigate the issue. Users who cannot upgrade should avoid cloning, fetching, or
    checking out untrusted repositories with Dulwich on Windows. After upgrading the NTFS validator is on by
    default on every platform, so no additional configuration is required. (CVE-2026-42305)

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-2026 advisory.

    Dulwich through 1.1.0 was found to be missing SSH host key verification in contrib/paramiko_vendor.py.
    (CVE-2026-38974)

    Arbitrary file write leading to remote code execution when cloning or checking out a malicious Git     repository on Windows.

    Dulwich's path-element validator accepted tree entries whose filenames contained bytes that Windows     interprets as structural path syntax:

    \ -- the Windows path separator. A single tree entry named .git\hooks\pre-commit.exe was treated as one     valid filename on POSIX but materialized as nested directories .git/hooks/pre-commit.exe on Windows,     planting a file inside the victim's .git directory. Git for Windows thenexecutes that hook on the next git     commit, giving the attacker arbitrary code execution in the victim's user context. The same primitive can     be used with ..\outside.txt to escape the work tree.: -- the NTFS alternate-data-stream marker.
    .git::$INDEX_ALLOCATION writes directly into the victim's .git entity, bypassing the .git-as-a-directory     check.git~ -- NTFS 8.3 short-name aliases of .git. Only the literal git1 was rejected; git2, git10, GIT1,     etc. were all accepted.Contributing configuration bugs made matters worse. The core.protectNTFS and     core.protectHFS settings were looked up under a wrong option name and so user-set values were silently     ignored, and core.protectNTFS only defaulted to true on Windows (Git upstream has defaulted it to true     everywhere since CVE-2019-1353). Both have been corrected.

    Anyone who clones, fetches, or checks out an untrusted repository with Dulwich on Windows - either through     the Dulwich CLI, porcelain.clone, or any downstream tool built on Dulwich - is impacted. POSIX clones are     not directly exploitable (on POSIX \ is a literal filename byte), but a POSIX user can unknowingly     propagate a malicious tree to Windows consumers via push or re-publication. (CVE-2026-42305)

    An uncontrolled-resource-consumption (memory exhaustion) denial-of-service vulnerability (CWE-400 /     CWE-789).

    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.

    Who is impacted: 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. (CVE-2026-47734)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-fbd55e52fb advisory.

    1.2.9, CVE fixes

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Dulwich is a pure-Python implementation of the Git file formats and protocols. Versions starting with     0.10.0 and prior to 1.2.5 have an arbitrary file write leading to remote code execution when cloning or     checking out a malicious Git repository on Windows. Dulwich's path-element validator accepted tree entries     whose filenames contained bytes that Windows interprets as structural path syntax. Contributing     configuration bugs made matters worse. The core.protectNTFS and core.protectHFS settings were looked up     under a wrong option name and so user-set values were silently ignored, and core.protectNTFS only     defaulted to true on Windows (Git upstream has defaulted it to true everywhere since CVE-2019-1353). Both     have been corrected. Anyone who clones, fetches, or checks out an untrusted repository with Dulwich on     Windows - either through the Dulwich CLI, porcelain.clone, or any downstream tool built on Dulwich - is     impacted. POSIX clones are not directly exploitable (on POSIX \ is a literal filename byte), but a POSIX     user can unknowingly propagate a malicious tree to Windows consumers via push or re-publication. This     issue is fixed in Dulwich 1.2.5. Users should upgrade to 1.2.5 or later. There is no effective pre-patch     workaround. On affected versions the core.protectNTFS configuration key was silently ignored, so setting     it to true does not mitigate the issue. Users who cannot upgrade should avoid cloning, fetching, or     checking out untrusted repositories with Dulwich on Windows. After upgrading the NTFS validator is on by     default on every platform, so no additional configuration is required. (CVE-2026-42305)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
458749	Echo: dulwich: security update to 1.2.5	Tenable Cloud Security	Echo Local Security Checks	Local	high
458749	Echo: dulwich: security update to 1.2.5	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
332007	Amazon Linux 2023 : python3-dulwich (ALAS2023-2026-2026)	Nessus	Amazon Linux Local Security Checks	Local	high
326391	Fedora 44 : python-dulwich (2026-fbd55e52fb)	Nessus	Fedora Local Security Checks	Local	high
442450	SCA: security update for dulwich (GHSA-897w-fcg9-f6xj)	Tenable Cloud Security	SCA Checks	Local	high
442450	SCA: security update for dulwich (GHSA-897w-fcg9-f6xj)	Tenable Self-Hosted Container Security	SCA Checks	Local	high
317714	Linux Distros Unpatched Vulnerability : CVE-2026-42305	Nessus	Misc.	Local	high

Detections

Analytics

CVE-2026-42305

high

Tenable Plugins

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high

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