Calling the ungetwc function on a FILE stream with wide characters encoded in a character set that has overlaps between its single byte and multi-byte character encodings, in the GNU C Library version 2.43 or earlier, may result in an attempt to read bytes before an allocated buffer, potentially resulting in unintentional disclosure of neighboring data in the heap, or a program crash. A bug in the wide character pushback implementation (_IO_wdefault_pbackfail in libio/wgenops.c) causes ungetwc() to operate on the regular character buffer (fp->_IO_read_ptr) instead of the actual wide-stream read pointer (fp->_wide_data->_IO_read_ptr). The program crash may happen in cases where fp->_IO_read_ptr is not initialized and hence points to NULL. The buffer under-read requires a special situation where the input character encoding is such that there are overlaps between single byte representations and multibyte representations in that encoding, resulting in spurious matches. The spurious match case is not possible in the standard Unicode character sets.

The remote SUSE Linux SLES12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:2440-1 advisory.

    - CVE-2026-5928: libio: Fix ungetwc operating on byte stream (bsc#1262464, BZ #33998)
    - CVE-2026-5450: stdio-common: Fix buffer overflow in scanf %mc (bsc#1262465, BZ #34008)
    - CVE-2026-4046: Use pending character state in IBM1390, IBM1399 character sets (bsc#1261206, BZ #33980)

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-2026:2333-1 advisory.

    This update for glibc fixes the following issues

    - CVE-2026-4046: assertion failure when converting inputs may be used to remotely crash an application     (bsc#1261206).
    - CVE-2026-5450: stdio-common: scanf %mc pattern will cause heap overflow when width > 1024 (bsc#1262465).
    - CVE-2026-5928: libio: ungetwc could be used to leak data on special conditions (bsc#1262464).

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.

According to the versions of the glibc packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

    Calling the scanf family of functions with a %mc (malloc'd character match) in the GNU C Library version     2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in     a one byte heap buffer overflow.(CVE-2026-5450)

    Calling the ungetwc function on a FILE stream with wide characters encoded in a character set that has     overlaps between its single byte and multi-byte character encodings, in the GNU C Library version 2.43 or     earlier, may result in an attempt to read bytes before an allocated buffer, potentially resulting in     unintentional disclosure of neighboring data in the heap, or a program crash.A bug in the wide character     pushback implementation (_IO_wdefault_pbackfail in libio/wgenops.c) causes ungetwc() to operate on the     regular character buffer (fp-_IO_read_ptr) instead of the actual wide-stream read pointer (fp-
    _wide_data-_IO_read_ptr). The program crash may happen in cases where fp-_IO_read_ptr is not     initialized and hence points to NULL. The buffer under-read requires a special situation where the input     character encoding is such that there are overlaps between single byte representations and multibyte     representations in that encoding, resulting in spurious matches. The spurious match case is not possible     in the standard Unicode character sets.(CVE-2026-5928)

    The iconv() function in the GNU C Library versions 2.43 and earlier may crash due to an assertion failure     when converting inputs from the IBM1390 or IBM1399 character sets, which may be used to remotely crash an     application.This vulnerability can be trivially mitigated by removing the IBM1390 and IBM1399 character     sets from systems that do not need them.(CVE-2026-4046)

Tenable has extracted the preceding description block directly from the EulerOS Virtualization glibc security advisory.

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

According to the versions of the glibc packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

    Calling the scanf family of functions with a %mc (malloc'd character match) in the GNU C Library version     2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in     a one byte heap buffer overflow.(CVE-2026-5450)

    Calling the ungetwc function on a FILE stream with wide characters encoded in a character set that has     overlaps between its single byte and multi-byte character encodings, in the GNU C Library version 2.43 or     earlier, may result in an attempt to read bytes before an allocated buffer, potentially resulting in     unintentional disclosure of neighboring data in the heap, or a program crash._x000D_
    _x000D_     A bug in the wide character pushback implementation (_IO_wdefault_pbackfail in libio/wgenops.c) causes     ungetwc() to operate on the regular character buffer (fp-_IO_read_ptr) instead of the actual wide-     stream read pointer (fp-_wide_data-_IO_read_ptr). The program crash may happen in cases where fp-
    _IO_read_ptr is not initialized and hence points to NULL. The buffer under-read requires a special     situation where the input character encoding is such that there are overlaps between single byte     representations and multibyte representations in that encoding, resulting in spurious matches. The     spurious match case is not possible in the standard Unicode character sets.(CVE-2026-5928)

    The iconv() function in the GNU C Library versions 2.43 and earlier may crash due to an assertion failure     when converting inputs from the IBM1390 or IBM1399 character sets, which may be used to remotely crash an     application._x000D_
    _x000D_
    _x000D_
    _x000D_     This vulnerability can be trivially mitigated by removing the IBM1390 and IBM1399 character sets from     systems that do not need them.(CVE-2026-4046)

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

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

An update of the glibc package has been released.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-4b7780802c advisory.

    This update provides various security fixes.

    * Buffer overflow in `scanf` `%mc` (CVE-2026-5450)
    * `ns_sprintrrf` buffer overreads (CVE-2026-6238)
    * `ns_sprintrrf` buffer overflow in TSIG record processing (CVE-2026-5435)
    * Memory corruption in `ungetwc` (CVE-2026-5928)
    * Assertion failure in `iconv` with IBM1390, IBM1399 charsets (CVE-2026-4046)


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 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-ced72ab158 advisory.

    This update provides various security fixes.

    * Buffer overflow in `scanf` `%mc` (CVE-2026-5450)
    * `ns_sprintrrf` buffer overreads (CVE-2026-6238)
    * `ns_sprintrrf` buffer overflow in TSIG record processing (CVE-2026-5435)
    * Memory corruption in `ungetwc` (CVE-2026-5928)
    * Assertion failure in `iconv` with IBM1390, IBM1399 charsets (CVE-2026-4046)


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.

  - Calling the ungetwc function on a FILE stream with wide characters encoded in a character set that has     overlaps between its single byte and multi-byte character encodings, in the GNU C Library version 2.43 or     earlier, may result in an attempt to read bytes before an allocated buffer, potentially resulting in     unintentional disclosure of neighboring data in the heap, or a program crash. A bug in the wide character     pushback implementation (_IO_wdefault_pbackfail in libio/wgenops.c) causes ungetwc() to operate on the     regular character buffer (fp->_IO_read_ptr) instead of the actual wide-stream read pointer     (fp->_wide_data->_IO_read_ptr). The program crash may happen in cases where fp->_IO_read_ptr is not     initialized and hence points to NULL. The buffer under-read requires a special situation where the input     character encoding is such that there are overlaps between single byte representations and multibyte     representations in that encoding, resulting in spurious matches. The spurious match case is not possible     in the standard Unicode character sets. (CVE-2026-5928)

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

ID	Name	Product	Family	Severity
321751	SUSE SLES12 Security Update : glibc (SUSE-SU-2026:2440-1)	Nessus	SuSE Local Security Checks	critical
321044	SUSE SLES15 Security Update : glibc (SUSE-SU-2026:2333-1)	Nessus	SuSE Local Security Checks	critical
320737	EulerOS Virtualization 2.13.1 : glibc (EulerOS-SA-2026-2370)	Nessus	Huawei Local Security Checks	critical
320705	EulerOS Virtualization 2.13.0 : glibc (EulerOS-SA-2026-2399)	Nessus	Huawei Local Security Checks	critical
320234	EulerOS 2.0 SP13 : glibc (EulerOS-SA-2026-2290)	Nessus	Huawei Local Security Checks	critical
320226	EulerOS 2.0 SP13 : glibc (EulerOS-SA-2026-2333)	Nessus	Huawei Local Security Checks	critical
317382	Photon OS 5.0: Glibc PHSA-2026-5.0-0857	Nessus	PhotonOS Local Security Checks	critical
312242	Fedora 43 : glibc (2026-4b7780802c)	Nessus	Fedora Local Security Checks	critical
311773	Fedora 44 : glibc (2026-ced72ab158)	Nessus	Fedora Local Security Checks	critical
308161	Linux Distros Unpatched Vulnerability : CVE-2026-5928	Nessus	Misc.	high

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CVE-2026-5928

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