A flaw exists in the nbdkit "blocksize" filter that can be triggered by a specific type of client request. When a client requests block status information for a very large data range, exceeding a certain limit, it causes an internal error in the nbdkit, leading to a denial of service.

The Rocky Linux 9.6 host has packages installed that are affected by a vulnerability as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1777021155 advisory.

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

The AlmaLinux 9.6 host has packages installed that are affected by a vulnerability as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1777021155 advisory.

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

The version of Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2025:0593 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2025-47712:
    A flaw exists in the nbdkit blocksize filter that can be triggered by a specific type of client request.
    When a client requests block status information for a very large data range, exceeding a certain limit, it     causes an internal error in the nbdkit, leading to a denial of service.

    CVE-2025-47711:
    There's a flaw in the nbdkit server when handling responses from its plugins regarding the status of data     blocks. If a client makes a specific request for a very large data range, and a plugin responds with an     even larger single block, the nbdkit server can encounter a critical internal error, leading to a denial-     of-service.

Tenable has extracted the preceding description block directly from the Tencent Linux 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.

  - Debian Linux - nbdkit - A flaw exists in the nbdkit blocksize filter that can be triggered by a specific     type of client request. When a client requests block status information for a very large data range,     exceeding a certain limit, it causes an internal error in the nbdkit, leading to a denial of service.  Red     Hat Enterprise Linux - nbd: nbdkit: Integer overflow triggers an assertion resulting in Denial of Service     Ubuntu Linux - A flaw exists in the nbdkit blocksize filter that can be triggered by a specific type of     client request. When a client requests block status information for a very large data range, exceeding a     certain limit, it causes an internal error in the nbdkit, leading to a denial of service. (CVE-2025-47712)

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

The version of nbdkit installed on the remote CBL Mariner 2.0 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the CVE-2025-47712 advisory.

  - A flaw exists in the nbdkit blocksize filter that can be triggered by a specific type of client request.
    When a client requests block status information for a very large data range, exceeding a certain limit, it     causes an internal error in the nbdkit, leading to a denial of service. (CVE-2025-47712)

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

The version of nbdkit installed on the remote Azure Linux 3.0 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the CVE-2025-47712 advisory.

  - A flaw exists in the nbdkit blocksize filter that can be triggered by a specific type of client request.
    When a client requests block status information for a very large data range, exceeding a certain limit, it     causes an internal error in the nbdkit, leading to a denial of service. (CVE-2025-47712)

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

The remote SUSE Linux SLES15 / SLES_SAP15 / openSUSE 15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2025:01889-1 advisory.

    Update to version 1.36.5.

    Security fixes:

    - CVE-2025-47712: integer overflow in blocksize filter when processing client block status requests larger     than 2**32       will trigger an assertion failure and cause a denial-of-service. (bsc#1243108).
    - CVE-2025-47711: off-by-one error when processing block status results from plugins on behalf of an NBD     client may       trigger an assertion failure and cause a denial of service (bsc#1243110).

    Other fixes and changes:

    - tests: Add test-blkio.sh to unconditional EXTRA_DIST rule.
    - Revert 'valgrind: Add suppression for liblzma bug'.
    - vddk: Move 'Unknown error' information to the manual.
    - ocaml Add better comments to the example plugin.
    - ocaml: Simplify pread operation.
    - ocaml: Define a struct handle to hold the OCaml handle.
    - ocaml: Add OCaml version to --dump-plugin output.
    - ocaml: Print callback name when an exception is printed.
    - ocaml: Combine all exception printing into a single macro.

Tenable has extracted the preceding description block directly from the SUSE 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 SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2025:01888-1 advisory.

    Update to version 1.40.6.

    Security fixes:

    - CVE-2025-47712: integer overflow in blocksize filter when processing client block status requests larger     than 2**32       will trigger an assertion failure and cause a denial-of-service. (bsc#1243108).
    - CVE-2025-47711: off-by-one error when processing block status results from plugins on behalf of an NBD     client may       trigger an assertion failure and cause a denial of service (bsc#1243110).

    Other fixes and changes:

    - golang: Support GCC 15.
    - openbsd: curl: Include pthread.h.
    - rust: Fix 'overindented' list in comment.
    - rust: Declare explicit extern 'C' API.
    - plugins/rust: Use CStr literals for static strings.
    - vddk: do_extents: Avoid reading partial chunk beyond the end of the disk.
    - vddk: do_extents: Exit the function if we hit req_one condition.
    - vddk: do_extents: Mark some local variables const.
    - vddk: Cache the disk size in the handle.
    - vddk: Include <stdbool.h>.
    - python: examples: Fix comment above API_VERSION constant.
    - tcl: Fix for Tcl 9.0 compatibility.
    - plugins/ocaml/NBDKit.ml: Sort bindings into order.
    - ocaml: Don't call abort if caml_c_thread_unregister fails.
    - ocaml: Use real addresses instead of (void*)<constant>s.
    - evil: Link to nbdkit_parse_probability(3).

Tenable has extracted the preceding description block directly from the SUSE 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 42 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2025-8a2d82f65a advisory.

    New upstream stable branch version 1.42.3



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 remote Fedora 41 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2025-bc02ec32fb advisory.

    New upstream stable branch version 1.40.6



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.

ID	Name	Product	Family	Type	Severity
359814	Rocky Linux 9.6 [TuxCare] Security Update: nbdkit / nbdkit-bash-completion / nbdkit-basic-filters / etc (ALMALINUX9.6:CLSA-2026:1777021155)	Nessus	Rocky Linux Local Security Checks	Local	medium
359598	AlmaLinux 9.6 [TuxCare] Security Update: nbdkit / nbdkit-bash-completion / nbdkit-basic-filters / etc (ALMALINUX9.6:CLSA-2026:1777021155)	Nessus	Alma Linux Local Security Checks	Local	medium
253451	TencentOS Server 4: nbdkit (TSSA-2025:0593)	Nessus	Tencent Local Security Checks	Local	medium
251247	Linux Distros Unpatched Vulnerability : CVE-2025-47712	Nessus	Misc.	Local	high
241877	CBL Mariner 2.0 Security Update: nbdkit (CVE-2025-47712)	Nessus	MarinerOS Local Security Checks	Local	medium
241860	Azure Linux 3.0 Security Update: nbdkit (CVE-2025-47712)	Nessus	Azure Linux Local Security Checks	Local	medium
240796	SUSE SLES15 / openSUSE 15 Security Update : nbdkit (SUSE-SU-2025:01889-1)	Nessus	SuSE Local Security Checks	Local	medium
240765	SUSE SLES15 Security Update : nbdkit (SUSE-SU-2025:01888-1)	Nessus	SuSE Local Security Checks	Local	medium
237951	Fedora 42 : nbdkit (2025-8a2d82f65a)	Nessus	Fedora Local Security Checks	Local	high
237230	Fedora 41 : nbdkit (2025-bc02ec32fb)	Nessus	Fedora Local Security Checks	Local	high

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CVE-2025-47712

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