CVE-2026-107168 Overview
CVE-2026-107168 is a denial-of-service vulnerability in m17n-lib, a multilingual text processing library. The flaw allows an attacker to supply a crafted input containing an invalid UTF-8 character sequence that forces the text parsing function into an infinite loop [CWE-835]. The condition drives sustained high CPU utilization and renders the affected application unresponsive. The issue requires local access and no privileges or user interaction to trigger.
Critical Impact
An attacker with local access can trigger an infinite loop in m17n-lib text parsing, exhausting CPU resources and causing denial of service in any application that uses the library to process untrusted text.
Affected Products
- m17n-lib (multilingual text processing library)
- Applications and desktop environments that link against m17n-lib for input method and text rendering
- Linux distributions that package m17n-lib (see the Red Hat CVE-2026-107168 Advisory)
Discovery Timeline
- 2026-10-07 - CVE CVE-2026-107168 published to NVD
- 2026-10-07 - Last updated in NVD database
Technical Details for CVE-2026-107168
Vulnerability Analysis
The vulnerability resides in the text parsing routine of m17n-lib. The library processes multilingual text and is widely used by input method frameworks and localization components on Linux systems. When the parser encounters a specific malformed UTF-8 byte sequence, its control loop fails to advance past the invalid bytes. The parser repeatedly re-evaluates the same offset, producing an infinite loop that saturates a CPU core.
Any process that calls the affected parsing function on attacker-controlled text becomes unresponsive. The impact is limited to availability, with no confidentiality or integrity consequences, but the affected process can remain stuck until terminated. Automated services that invoke m17n-lib on untrusted input are particularly exposed.
Root Cause
The root cause is improper handling of invalid UTF-8 sequences in the parser's byte-advancement logic. The function does not guarantee forward progress when it encounters a byte sequence that violates UTF-8 encoding rules. Classified as [CWE-835] Loop with Unreachable Exit Condition, the defect lets a malformed codepoint hold the parser in a state where no iteration consumes input or satisfies the exit predicate.
Attack Vector
Exploitation requires local delivery of a crafted text payload to any application that routes input through m17n-lib. Typical delivery paths include files opened by text editors, clipboard content handled by input methods, and localized strings processed by desktop utilities. No authentication or user interaction is required beyond causing the target process to parse the malicious input. The result is CPU exhaustion of the affected process rather than code execution or data disclosure.
No verified public exploit code is available. Refer to the Red Hat Bug Report #2547409 for technical discussion.
Detection Methods for CVE-2026-107168
Indicators of Compromise
- Processes linked against libm17n consuming 100% of a CPU core for extended periods with no corresponding workload.
- Input method daemons such as ibus-daemon or applications using m17n modules becoming unresponsive after processing specific text input.
- User reports of desktop freezes or hangs correlated with opening files containing non-ASCII content.
Detection Strategies
- Monitor process CPU utilization for long-lived single-threaded spikes in binaries that load libm17n.so.
- Collect stack traces from hung processes with gdb or perf and look for frames inside m17n-lib parsing routines.
- Audit installed package versions against vendor advisories to identify hosts running vulnerable builds of m17n-lib.
Monitoring Recommendations
- Alert on sustained CPU saturation by user-space processes that normally remain idle, particularly input method and localization services.
- Track crash and hang telemetry from endpoint agents to surface repeated restarts of m17n-lib consumers.
- Correlate file open events for .txt, .po, or input-method configuration files with subsequent CPU anomalies.
How to Mitigate CVE-2026-107168
Immediate Actions Required
- Inventory all systems with m17n-lib installed and identify applications that depend on it.
- Apply vendor-supplied security updates as soon as they are available from your Linux distribution.
- Restrict processing of untrusted text files on multi-user systems where m17n-lib is loaded.
Patch Information
Consult the Red Hat CVE-2026-107168 Advisory for distribution-specific patch availability and errata. Track upstream m17n-lib releases through your package manager and apply updates once vendors publish fixed builds. The Red Hat Bug Report #2547409 tracks remediation progress.
Workarounds
- Terminate hung processes manually with kill when CPU saturation is observed, pending patch deployment.
- Apply CPU usage limits via cgroups or systemd resource controls to contain runaway processes that invoke m17n-lib.
- Limit the exposure of input method frameworks to text originating from untrusted sources until patched packages are installed.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.