A vulnerability exists in the chroot utility of uutils coreutils when using the --userspec option. The utility resolves the user specification via getpwnam() after entering the chroot but before dropping root privileges. On glibc-based systems, this can trigger the Name Service Switch (NSS) to load shared libraries (e.g., libnss.so.2) from the new root directory. If the NEWROOT is writable by an attacker, they can inject a malicious NSS module to execute arbitrary code as root, facilitating a full container escape or privilege escalation.

A vulnerability in the rm utility of uutils coreutils allows a bypass of the --preserve-root protection. The implementation uses a path-string check rather than comparing device and inode numbers to identify the root directory. An attacker or accidental user can bypass this safeguard by using a symbolic link that resolves to the root directory (e.g., /tmp/rootlink -> /), potentially leading to the unintended recursive deletion of the entire root filesystem.

Chmoder::chmod() only compares the literal argument against Path::new("/"), so the --preserve-root guard is bypassed by any path that resolves to root — a symlink to / or simply /../.

if self.recursive && self.preserveroot && file == Path::new("/") { return Err(ChmodError::PreserveRoot("/".tostring()).into()); }

PoC — recursively chmods the entire filesystem to 000 despite --preserve-root:

chmod -R --preserve-root 000 /../ -v

Impact: --preserve-root is the documented safeguard against destructive recursive operations on /. Bypassing it allows chmod -R to alter permissions across the whole filesystem, causing a complete system breakdown. Recommendation: canonicalize the target path before comparing against root.

Remediation: Acknowledged by Canonical; fixed in commit 413055b3.

--- Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.1. Credit: Zellic.

A vulnerability in uutils coreutils mkfifo allows for the unauthorized modification of permissions on existing files. When mkfifo fails to create a FIFO because a file already exists at the target path, it fails to terminate the operation for that path and continues to execute a follow-up setpermissions call. This results in the existing file's permissions being changed to the default mode (often 644 after umask), potentially exposing sensitive files such as SSH private keys to other users on the system.

A Time-of-Check to Time-of-Use (TOCTOU) race condition exists in the mkfifo utility of uutils coreutils. The utility creates a FIFO and then performs a path-based chmod to set permissions. A local attacker with write access to the parent directory can swap the newly created FIFO for a symbolic link between these two operations. This redirects the chmod call to an arbitrary file, potentially enabling privilege escalation if the utility is run with elevated privileges.

The cp utility in uutils coreutils fails to properly handle setuid and setgid bits when ownership preservation fails. When copying with the -p (preserve) flag, the utility applies the source mode bits even if the chown operation is unsuccessful. This can result in a user-owned copy retaining original privileged bits, creating unexpected privileged executables that violate local security policies. This differs from GNU cp, which clears these bits when ownership cannot be preserved.

The mv utility in uutils coreutils improperly handles directory trees containing symbolic links during moves across filesystem boundaries. Instead of preserving symlinks, the implementation expands them, copying the linked targets as real files or directories at the destination. This can lead to resource exhaustion (disk space or time) if symlinks point to large external directories, unexpected duplication of sensitive data into unintended locations, or infinite recursion and repeated copying in the presence of symlink loops.

A Time-of-Check to Time-of-Use (TOCTOU) vulnerability exists in the split utility of uutils coreutils. The program attempts to prevent data loss by checking for identity between input and output files using their file paths before initiating the split operation. However, the utility subsequently opens the output file with truncation after this path-based validation is complete. A local attacker with write access to the directory can exploit this race window by manipulating mutable path components (e.g., swapping a path with a symbolic link). This can cause split to truncate and write to an unintended target file, potentially including the input file itself or other sensitive files accessible to the process, leading to permanent data loss.

copyfile in install/src/install.rs removes the destination then recreates it by pathname via File::create / fs::copy without OEXCL/createnew. Between the unlink and the recreate, a local attacker with write access to the destination directory can drop in a symlink and redirect the write.

Impact: when install runs privileged into an attacker-writable directory (staging/build paths), the race allows redirecting writes to arbitrary files and overwriting sensitive system files (/etc/passwd, /etc/shadow). Recommendation: create atomically with createnew/OEXCL and copy via the opened fd rather than reopening by path.

Remediation: Acknowledged by Canonical; fixed in commit b5bbabc1.

--- Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.50. Credit: Zellic.

The touch utility in uutils coreutils is vulnerable to a Time-of-Check to Time-of-Use (TOCTOU) race condition during file creation. When the utility identifies a missing path, it later attempts creation using File::create(), which internally uses OTRUNC. An attacker can exploit this window to create a file or swap a symlink at the target path, causing touch to truncate an existing file and leading to permanent data loss.

A Time-of-Check to Time-of-Use (TOCTOU) vulnerability exists in the install utility of uutils coreutils when using the -D flag. The command creates parent directories and subsequently performs a second path resolution to create the target file, neither of which is anchored to a directory file descriptor. An attacker with concurrent write access can replace a path component with a symbolic link between these operations, redirecting the privileged write to an arbitrary file system location.

A Time-of-Check to Time-of-Use (TOCTOU) race condition exists in the mv utility of uutils coreutils during cross-device operations. The utility removes the destination path before recreating it through a copy operation. A local attacker with write access to the destination directory can exploit this window to replace the destination with a symbolic link. The subsequent privileged move operation will follow the symlink, allowing the attacker to redirect the write and overwrite an arbitrary target file with contents from the source.

A Time-of-Check to Time-of-Use (TOCTOU) vulnerability exists in the chcon utility of uutils coreutils during recursive operations. The implementation resolves recursive targets using a fresh path lookup (via ftsaccpath) rather than binding the traversal and label application to the specific directory state encountered during traversal. Because these operations are not anchored to file descriptors, a local attacker with write access to a directory tree can exploit timing-sensitive rename or symbolic link races to redirect a privileged recursive relabeling operation to unintended files or directories. This vulnerability breaks the hardening expectations for SELinux administration workflows and can lead to the unauthorized modification of security labels on sensitive system objects.

rm -rf . is correctly refused, but cleantrailingslashes normalizes ./// to ./ while pathiscurrentorparentdirectory only matches ./.. (and /.//..), not ./ or ../. So rm -rf ./ recursively deletes the directory's contents and then prints a misleading cannot remove './': Invalid input.

Impact: all files/subdirectories in the current directory are silently deleted; the misleading error makes users miss the recovery window. Recommendation: handle trailing-slash variants in pathiscurrentorparentdirectory.

Remediation: Acknowledged by Canonical; fixed in commit d0e5af23.

--- Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.60. Credit: Zellic.

Upstream tracking issue: https://github.com/uutils/coreutils/issues/9749 · CVE-2026-35363

The sort utility in uutils coreutils is vulnerable to a process panic when using the --files0-from option with inputs containing non-UTF-8 filenames. The implementation enforces UTF-8 encoding and utilizes expect(), causing an immediate crash when encountering valid but non-UTF-8 paths. This diverges from GNU sort, which treats filenames as raw bytes. A local attacker can exploit this to crash the utility and disrupt automated pipelines.

The cp utility in uutils coreutils, when performing recursive copies (-R), incorrectly treats character and block device nodes as stream sources rather than preserving them. Because the implementation reads bytes into regular files at the destination instead of using mknod, device semantics are destroyed (e.g., /dev/null becomes a regular file). This behavior can lead to runtime denial of service through disk exhaustion or process hangs when reading from unbounded device nodes.

A logic error in the cut utility of uutils coreutils causes the program to incorrectly interpret the literal two-byte string '' (two single quotes) as an empty delimiter. The implementation mistakenly maps this string to the NUL character for both the -d (delimiter) and --output-delimiter options. This vulnerability can lead to silent data corruption or logic errors in automated scripts and data pipelines that process strings containing these characters, as the utility may unintentionally split or join data on NUL bytes rather than the intended literal characters.

A logic error in the ln utility of uutils coreutils causes the program to reject source paths containing non-UTF-8 filename bytes when using target-directory forms (e.g., ln SOURCE... DIRECTORY). While GNU ln treats filenames as raw bytes and creates the links correctly, the uutils implementation enforces UTF-8 encoding, resulting in a failure to stat the file and a non-zero exit code. In environments where automated scripts or system tasks process valid but non-UTF-8 filenames common on Unix filesystems, this divergence causes the utility to fail, leading to a local denial of service for those specific operations.

A flaw in the ChownExecutor used by uutils coreutils chown and chgrp causes the utilities to return an incorrect exit code during recursive operations. The final exit code is determined only by the last file processed. If the last operation succeeds, the command returns 0 even if earlier ownership or group changes failed due to permission errors. This can lead to security misconfigurations where administrative scripts incorrectly assume that ownership has been successfully transferred across a directory tree.

In Chmoder::chmod() the recursive branch overwrites the running result instead of accumulating it, so the exit code reflects only the last file processed:

if self.recursive { r = self.walkdirwithcontext(file, true); // overwrites r } else { r = self.chmodfile(file).and(r); }

PoC: GNU returns 1 when a file fails; uutils returns 0 if the last entry succeeds:

$ chmod -R 0755 chmod-bug/root chmod-bug/user # GNU -> ret=1 $ uutils chmod -R 0755 chmod-bug/root chmod-bug/user # -> ret=0

Impact: scripts relying on the exit code get a false success signal while some files retained restrictive/unexpected permissions, leading to access-control misconfigurations. Recommendation: accumulate errors during traversal.

Remediation: Acknowledged by Canonical; fixed in commit abd581f6.

--- Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.2. Credit: Zellic.

kill -1 is incorrectly parsed as a positional pid = -1; combined with the default SIGTERM this calls kill(-1, SIGTERM), signaling nearly every process the caller can see. GNU kill recognizes -1/-9 as signals and reports "not enough arguments".

$ kill -1 # uutils: kill(-1, SIGTERM) -> mass termination / crash $ kill -1 # GNU: kill: not enough arguments

Impact: a user running kill -1 mass-terminates processes, potentially crashing the system. Recommendation: parse -N as a signal number, and error with "not enough arguments" when no PID is given.

Remediation: Acknowledged by Canonical; fixed in commit cae94028.

--- Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.70. Credit: Zellic.

A vulnerability in the tail utility of uutils coreutils allows for the exfiltration of sensitive file contents when using the --follow=name option. Unlike GNU tail, the uutils implementation continues to monitor a path after it has been replaced by a symbolic link, subsequently outputting the contents of the link's target. In environments where a privileged user (e.g., root) monitors a log directory, a local attacker with write access to that directory can replace a log file with a symlink to a sensitive system file (such as /etc/shadow), causing tail to disclose the contents of the sensitive file.

A logic error in the ln utility of uutils coreutils allows the utility to dereference a symbolic link target even when the --no-dereference (or -n) flag is explicitly provided. The implementation previously only honored the "no-dereference" intent if the --force (overwrite) mode was also enabled. This flaw causes ln to follow a symbolic link that points to a directory and create new links inside that target directory instead of treating the symbolic link itself as the destination. In environments where a privileged user or system script uses ln -n to update a symlink, a local attacker could manipulate existing symbolic links to redirect file creation into sensitive directories, potentially leading to unauthorized file creation or system misconfiguration.

The cp utility in uutils coreutils is vulnerable to an information disclosure race condition. Destination files are initially created with umask-derived permissions (e.g., 0644) before being restricted to their final mode (e.g., 0600) later in the process. A local attacker can race to open the file during this window; once obtained, the file descriptor remains valid and readable even after the permissions are tightened, exposing sensitive or private file contents.

A Time-of-Check to Time-of-Use (TOCTOU) vulnerability exists in the mv utility of uutils coreutils during cross-device moves. The extended attribute (xattr) preservation logic uses multiple path-based system calls that perform fresh path-to-inode lookups for each operation. A local attacker with write access to the directory can exploit this race to swap files between calls, causing the destination file to receive an inconsistent mix of security xattrs, such as SELinux labels or file capabilities.

A Time-of-Check to Time-of-Use (TOCTOU) vulnerability in the cp utility of uutils coreutils allows an attacker to bypass no-dereference intent. The utility checks if a source path is a symbolic link using path-based metadata but subsequently opens it without the ONOFOLLOW flag. An attacker with concurrent write access can swap a regular file for a symbolic link during this window, causing a privileged cp process to copy the contents of arbitrary sensitive files into a destination controlled by the attacker.

The mknod utility in uutils coreutils fails to handle security labels atomically by creating device nodes before setting the SELinux context. If labeling fails, the utility attempts cleanup using std::fs::removedir, which cannot remove device nodes or FIFOs. This leaves mislabeled nodes behind with incorrect default contexts, potentially allowing unauthorized access to device nodes that should have been restricted by mandatory access controls.

The comm utility in uutils coreutils incorrectly consumes data from non-regular file inputs before performing comparison operations. The arefilesidentical function opens and reads from both input paths to compare content without first verifying if the paths refer to regular files. If an input path is a FIFO or a pipe, this pre-read operation drains the stream, leading to silent data loss before the actual comparison logic is executed. Additionally, the utility may hang indefinitely if it attempts to pre-read from infinite streams like /dev/zero.

The id utility in uutils coreutils miscalculates the groups= section of its output. The implementation uses a user's real GID instead of their effective GID to compute the group list, leading to potentially divergent output compared to GNU coreutils. Because many scripts and automated processes rely on the output of id to make security-critical access-control or permission decisions, this discrepancy can lead to unauthorized access or security misconfigurations.

The printenv utility in uutils coreutils fails to display environment variables containing invalid UTF-8 byte sequences. While POSIX permits arbitrary bytes in environment strings, the uutils implementation silently skips these entries rather than printing the raw bytes. This vulnerability allows malicious environment variables (e.g., adversarial LDPRELOAD values) to evade inspection by administrators or security auditing tools, potentially allowing library injection or other environment-based attacks to go undetected.