Stack overflow in nscd due to unbounded alloca use

A flaw was found in tar. A remote attacker could exploit this vulnerability by crafting a malicious archive, leading to hidden file injection with fully attacker-controlled content. This bypasses pre-extraction inspection mechanisms, potentially allowing an attacker to introduce malicious files onto a system without detection.

A flaw was found in GNU tar. The --one-top-level option is intended to confine extraction under a designated directory, but hardlink targets from the archive are not confined the same way and are resolved relative to the extraction working directory (or the directory given with -C). A crafted archive can create hardlinks inside the --one-top-level directory that point to files outside it. If a suitable symbolic link already exists under the extraction working directory, hardlinking to that symlink can bypass tar's usual symlink-based path protections and allow writing outside the intended top-level directory during a single extraction. Users who rely on --one-top-level as a security boundary when extracting untrusted archives may be affected.

A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename handling allows a local attacker with write access to a directory being backed up to influence the restore process if the attacker has access to the system where the restore is being performed. During restoration, files or directories may be created, renamed or overwritten outside the intended extraction directory. This could lead to unauthorized file modification or, in some cases, privilege escalation. Exploitation does not require the attacker to modify or craft the archive, and standard backup and restore workflows—including extracting into a newly created directory without using the -P option do not mitigate the issue.

Summary: GNU tar allows malformed archives where non-data-bearing typeflags (symlink, char device, block device, FIFO) contain a non-zero size field, leading to inconsistent behavior between listing (tar -t) and extraction (tar -x). This results in stream desynchronization and enables hidden file injection. Requirements to exploit: An attacker only needs the ability to supply a crafted tar archive to a target system that performs pre-extraction inspection using tar -t (or equivalent API) and later extracts it using GNU tar. No privileges or user interaction beyond extraction are required.

Patch Available: no

Version Fixed: N/A

Impact: Hidden file injection with fully attacker-controlled content

Bypass of pre-extraction inspection mechanisms

Single-implementation inconsistency (no cross-tool pipeline required)

Attack complexity: Low (crafted archive is < 3 KB, no special privileges)

Affected typeflags: '2', '3', '4', '6' (4 of 5 non-data typeflags)

Steps to reproduce if available:

Generate a crafted archive with a non-data-bearing typeflag (e.g., chardev) and non-zero size.

List contents

tar -tf crafted.tar

→ injected file is NOT shown

Extract archive:

tar -xf crafted.tar

Observe additional file created on disk that was not present in listing output.

A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename handling allows a local attacker with write access to a directory being backed up to influence the restore process if the attacker has access to the system where the restore is being performed. During restoration, files or directories may be created, renamed or overwritten outside the intended extraction directory. This could lead to unauthorized file modification or, in some cases, privilege escalation. Exploitation does not require the attacker to modify or craft the archive, and standard backup and restore workflows—including extracting into a newly created directory without using the -P option do not mitigate the issue.

GNU Emacs < 31.0.91 Heap Over-Read via PBM/PPM/PGM Image Loader

tar.Reader does not set a maximum size on the number of sparse region data blocks in GNU tar pax 1.0 sparse files. A maliciously-crafted archive containing a large number of sparse regions can cause a Reader to read an unbounded amount of data from the archive into memory. When reading from a compressed source, a small compressed input can result in large allocations.

GNU cpio contains a Path Traversal vulnerability in its tar archive extraction functionality. When extracting a tar archive in copy-in mode with the --no-absolute-filenames option, the extracted file name is normalized but the tar hard-link target is passed to the linktoname function without equivalent sanitization before calling link function. A tar archive provided by an attacker, containing a hard-link entry whose linkname is set to an absolute path outside the extraction directory, can cause cpio to create a hard link to an existing file outside the intended extraction directory, breaking the expected guarantee of --no-absolute-filenames and allowing archive-controlled linkage to external files.

GNU cpio is vulnerable to an uncontrolled memory allocation in the makepath function at src/makepath.c. The function uses alloca to allocate stack memory based on the length of argpath, which is derived from an archive-controlled pathname during extraction. A malicious cpio archive containing a sufficiently long nested pathname causes an unbounded stack allocation, resulting in a stack overflow and crash of the cpio process. An attacker who can supply a crafted cpio archive to a victim who extracts it can cause a denial of service.

GNU cpio is vulnerable to improper encoding or escaping of output in its archive member listing functionality. When listing archive members via cpio -it, member names are printed directly to output without quoting or escaping. An attacker can craft a cpio archive containing member names with embedded newline characters or ANSI escape sequences, causing forged listing entries or terminal control sequence injection when the listing is displayed.

A flaw was found in the GNU Binutils (Binary Utilities) linker. This vulnerability, a heap-buffer-overflow read (CWE-125), occurs when the linker processes a specially crafted 32-bit XCOFF (Extended Common Object File Format) object file. An attacker could exploit this by providing a malicious file, leading to an out-of-bounds read of memory. This can result in information disclosure, potentially revealing sensitive heap data, and a Denial of Service (DoS) due to the linker crashing.

Arbitrary Output Location Change in GNU Bison

Arbitrary Command Execution in GNU Bison

Buffer overread in nsprintrrf with corrupted RDATA field

A flaw was found in GNU Coreutils. The sort utility's begfield() function is vulnerable to a heap buffer under-read. The program may access memory outside the allocated buffer if a user runs a crafted command using the traditional key format. A malicious input could lead to a crash or leak sensitive data.

A flaw was found in binutils, specifically within the readelf utility. This vulnerability allows a local attacker to cause a Denial of Service (DoS) by tricking a user into processing a specially crafted Executable and Linkable Format (ELF) file. The exploitation of this flaw can lead to the system becoming unresponsive due to excessive resource consumption or a program crash.

A flaw was found in the GNU Binutils BFD library, a widely used component for handling binary files such as object files and executables. The issue occurs when processing specially crafted XCOFF object files, where a relocation type value is not properly validated before being used. This can cause the program to read memory outside of intended bounds. As a result, affected tools may crash or expose unintended memory contents, leading to denial-of-service or limited information disclosure risks.

GNU Tar through 1.35 allows file overwrite via directory traversal in crafted TAR archives, with a certain two-step process. First, the victim must extract an archive that contains a ../ symlink to a critical directory. Second, the victim must extract an archive that contains a critical file, specified via a relative pathname that begins with the symlink name and ends with that critical file's name. Here, the extraction follows the symlink and overwrites the critical file. This bypasses the protection mechanism of "Member name contains '..'" that would occur for a single TAR archive that attempted to specify the critical file via a ../ approach. For example, the first archive can contain "x - ../../../../../home/victim/.ssh" and the second archive can contain x/authorizedkeys. This can affect server applications that automatically extract any number of user-supplied TAR archives, and were relying on the blocking of traversal. This can also affect software installation processes in which "tar xf" is run more than once (e.g., when installing a package can automatically install two dependencies that are set up as untrusted tarballs instead of official packages). NOTE: the official GNU Tar manual has an otherwise-empty directory for each "tar xf" in its Security Rules of Thumb; however, third-party advice leads users to run "tar xf" more than once into the same directory.

Passing an effectively empty string to the ,ccs= syntax extension of the mode argument in the fopen function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled.

This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for ccs should not pass them through without validation.

A flaw was found in GNU nano's multi-buffer error message handling. When a user opens multiple files at startup and one triggers an ALERT-level error, a specially crafted filename containing printf format specifiers can be reinterpreted. This format string vulnerability may allow an attacker to achieve stack information disclosure, cause a denial of service (crash), or potentially perform arbitrary memory writes.

This is a vulnerability report sent to us through https://issues.redhat.com/browse/PSIRTSUPT-17918 and was created using the PoC auto-triage agents. It contains hints on the vulnerability extracted by the IA and the full report. ALWAYS review it before any action. Once working on this, don't forget to also update the JSM ticket.

Multiple Use-After-Free vulnerabilities were found in the addarchiveelement function in ld/ldmain.c of the GNU linker (ld), a component of binutils. The root cause is that pluginmaybeclaim() in ld/plugin.c frees the original BFD object via bfdclose/bfddeletebfd when entry->thebfd->myarchive == NULL, but the caller retains both the original abfd parameter and a shallow copy (originput.thebfd) as dangling pointers. These dangling pointers are subsequently dereferenced at three distinct locations in addarchiveelement:

1. Line ~1442: accessing abfd->myarchive via bfdusrdata(abfd->myarchive) 2. Line ~1493: multiple accesses to abfd and abfd->myarchive in a conditional check and bfdgetfilename call 3. Line ~1525: dereferencing the shallow copy originput.thebfd->myarchive in trace/verbose logging

The vulnerability is triggered when LTO plugins are active (linkinfo.ltopluginactive is true) and the input object has abfd->myarchive == NULL, which is a valid state for standalone object files. Red Hat builds binutils with --enable-plugins and --enable-lto, confirming the vulnerable code path is compiled in and reachable.

An attacker who can supply a crafted object or archive file to a build process using LTO-enabled linking could exploit this flaw to cause a denial of service (linker crash via segmentation fault). Arbitrary code execution is theoretically possible through heap manipulation but is substantially mitigated by hardening measures including stack protector, FORTIFYSOURCE, ASLR, and PIE.

The attack surface is limited to build-time environments — the linker is a development tool not exposed in production runtime. The most realistic exploitation scenario is a supply chain attack introducing a crafted object file as a build dependency in CI/CD pipelines or development environments.

A flaw was found in nano. A local user could exploit a format string vulnerability in the statusline() function. By creating a directory with a name containing printf specifiers, the application attempts to display this name, leading to a segmentation fault (SEGV). This results in a Denial of Service (DoS) for the nano application.

A flaw was found in the readelf utility of the binutils package. A local attacker could exploit two Denial of Service (DoS) vulnerabilities by providing a specially crafted Executable and Linkable Format (ELF) file. One vulnerability, a resource exhaustion (CWE-400), can lead to an out-of-memory condition. The other, a null pointer dereference (CWE-476), can cause a segmentation fault. Both issues can result in the readelf utility becoming unresponsive or crashing, leading to a denial of service.

A vulnerability in the GRUB2 bootloader has been identified in the normal module. This flaw, a memory Use After Free issue, occurs because the normalexit command is not properly unregistered when its related module is unloaded. An attacker can exploit this condition by invoking the command after the module has been removed, causing the system to improperly access a previously freed memory location. This leads to a system crash or possible impacts in data confidentiality and integrity.

A vulnerability has been identified in the GRUB2 bootloader's normal command that poses an immediate Denial of Service (DoS) risk. This flaw is a Use-after-Free issue, caused because the normal command is not properly unregistered when the module is unloaded. An attacker who can execute this command can force the system to access memory locations that are no longer valid. Successful exploitation leads directly to system instability, which can result in a complete crash and halt system availability. Impact on the data integrity and confidentiality is also not discarded.

A vulnerability has been identified in the GRUB (Grand Unified Bootloader) component. This flaw occurs because the bootloader mishandles string conversion when reading information from a USB device, allowing an attacker to exploit inconsistent length values. A local attacker can connect a maliciously configured USB device during the boot sequence to trigger this issue. A successful exploitation may lead GRUB to crash, leading to a Denial of Service. Data corruption may be also possible, although given the complexity of the exploit the impact is most likely limited.

A use-after-free vulnerability has been identified in the GNU GRUB (Grand Unified Bootloader). The flaw occurs because the file-closing process incorrectly retains a memory pointer, leaving an invalid reference to a file system structure. An attacker could exploit this vulnerability to cause grub to crash, leading to a Denial of Service. Possible data integrity or confidentiality compromise is not discarded.

A vulnerability has been identified in the GRUB2 bootloader's network module that poses an immediate Denial of Service (DoS) risk. This flaw is a Use-after-Free issue, caused because the netsetvlan command is not properly unregistered when the network module is unloaded from memory. An attacker who can execute this command can force the system to access memory locations that are no longer valid. Successful exploitation leads directly to system instability, which can result in a complete crash and halt system availability

A flaw was found in systems utilizing LUKS-encrypted disks with GRUB configured for TPM-based auto-decryption. When GRUB is set to automatically decrypt disks using keys stored in the TPM, it reads the decryption key into system memory. If an attacker with physical access can corrupt the underlying filesystem superblock, GRUB will fail to locate a valid filesystem and enter rescue mode. At this point, the disk is already decrypted, and the decryption key remains loaded in system memory. This scenario may allow an attacker with physical access to access the unencrypted data without any further authentication, thereby compromising data confidentiality. Furthermore, the ability to force this state through filesystem corruption also presents a data integrity concern.