cut routes -z -d '' through a special newline-delimiter path that ignores the -s only-delimited flag, emitting whole undelimited records (plus NUL) that should be suppressed. Pipelines relying on cut -s to drop undelimited records process data that should be filtered. printf 'abc' | cut -z -d '' -s -f 1 | od -An -tx1 # GNU: no output ; uutils: 61 62 63 00

--- Zellic private finding (zellic-ext/coreutils-private PR #102). Reported in the Zellic uutils coreutils Program Security Assessment (for Canonical, Jan 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242.

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 tr utility of uutils coreutils causes the program to incorrectly define the [:graph:] and [:print:] character classes. The implementation mistakenly includes the ASCII space character (0x20) in the [:graph:] class and excludes it from the [:print:] class, effectively reversing the standard behavior established by POSIX and GNU coreutils. This vulnerability leads to unintended data modification or loss when the utility is used in automated scripts or data-cleaning pipelines that rely on standard character class semantics. For example, a command executed to delete all graphical characters while intending to preserve whitespace will incorrectly delete all ASCII spaces, potentially resulting in data corruption or logic failures in downstream processing.

A logic error in the expr utility of uutils coreutils causes the program to evaluate parenthesized subexpressions during the parsing phase rather than at the execution phase. This implementation flaw prevents the utility from performing proper short-circuiting for logical OR (|) and AND (&) operations. As a result, arithmetic errors (such as division by zero) occurring within "dead" branches, branches that should be ignored due to short-circuiting, are raised as fatal errors. This divergence from GNU expr behavior can cause guarded expressions within shell scripts to fail with hard errors instead of returning expected boolean results, leading to premature script termination and breaking GNU-compatible shell control flow.

A logic error in the env utility of uutils coreutils causes a failure to correctly parse command-line arguments when utilizing the -S (split-string) option. In GNU env, backslashes within single quotes are treated literally (with the exceptions of \\ and \'). However, the uutils implementation incorrectly attempts to validate these sequences, resulting in an "invalid sequence" error and an immediate process termination with an exit status of 125 when encountering valid but unrecognized sequences like \a or \x. This divergence from GNU behavior breaks compatibility for automated scripts and administrative workflows that rely on standard split-string semantics, leading to a local denial of service for those operations.

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.

A logic error in the split utility of uutils coreutils causes the corruption of output filenames when provided with non-UTF-8 prefix or suffix inputs. The implementation utilizes tostringlossy() when constructing chunk filenames, which automatically rewrites invalid byte sequences into the UTF-8 replacement character (U+FFFD). This behavior diverges from GNU split, which preserves raw pathname bytes intact. In environments utilizing non-UTF-8 encodings, this vulnerability leads to the creation of files with incorrect names, potentially causing filename collisions, broken automation, or the misdirection of output data.

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.

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 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 id utility in uutils coreutils exhibits incorrect behavior in its "pretty print" output when the real UID and effective UID differ. The implementation incorrectly uses the effective GID instead of the effective UID when performing a name lookup for the effective user. This results in misleading diagnostic output that can cause automated scripts or system administrators to make incorrect decisions regarding file permissions or access control.

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.

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 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.

The nohup utility in uutils coreutils creates its default output file, nohup.out, without specifying explicit restricted permissions. This causes the file to inherit umask-based permissions, typically resulting in a world-readable file (0644). In multi-user environments, this allows any user on the system to read the captured stdout/stderr output of a command, potentially exposing sensitive information. This behavior diverges from GNU coreutils, which creates nohup.out with owner-only (0600) permissions.

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.

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) 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.

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 safetraversal module in uutils coreutils, which provides protection against Time-of-Check to Time-of-Use (TOCTOU) symlink races using file-descriptor-relative syscalls, is incorrectly limited to Linux targets. On other Unix-like systems such as macOS and FreeBSD, the utility fails to utilize these protections, leaving directory traversal operations vulnerable to symlink race conditions.

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 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 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 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.

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 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.

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.

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.

The mkdir utility in uutils coreutils incorrectly applies permissions when using the -m flag by creating a directory with umask-derived permissions (typically 0755) before subsequently changing them to the requested mode via a separate chmod system call. In multi-user environments, this introduces a brief window where a directory intended to be private is accessible to other users, potentially leading to unauthorized data access.

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.