CVE-2026-48813: 
Python vulnerability analysis and mitigation

CVE-2026-48813 is an improper input neutralization vulnerability in Flawfinder, a static analysis tool for C/C++ source code, that enables Terminal/ANSI Escape Sequence Injection and XML Injection via untrusted filenames and source text. All versions prior to 2.0.20 are affected. The vulnerability was initially reported by Dan Lenz, with additional issues discovered by project leader David A. Wheeler; the advisory was published on May 23, 2026, and the patch (version 2.0.20) was released on May 16, 2026. It carries a CVSS v4.0 base score of 8.7 (High) (GitHub Advisory, Flawfinder Advisory).

The root cause is CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), where untrusted fields — including filenames, categories, and code context text — are passed unsanitized into flawfinder's output routines. An attacker who can supply files with specially crafted names containing ANSI escape sequences can manipulate terminal rendering, potentially hiding scan results from human reviewers. Additionally, the output_sonar() function does not sanitize inputs before generating SonarQube XML reports, allowing injection of arbitrary XML attributes, and CSV report generation is similarly vulnerable to format corruption. Exploitation requires that a developer or CI pipeline runs flawfinder against attacker-controlled or malicious file inputs (GitHub Advisory, Flawfinder Advisory).

Successful exploitation primarily affects the integrity of flawfinder's output: an attacker can spoof terminal output to hide critical security findings from reviewers, corrupt CSV report formats, or inject arbitrary XML attributes into SonarQube vulnerability reports via output_sonar(). The most significant real-world risk is that security scan results could be silently suppressed or falsified, causing developers to believe code is safe when it is not. There is no direct confidentiality or availability impact, and the vulnerability does not enable remote code execution or lateral movement (GitHub Advisory, Red Hat Bugzilla).

A public proof-of-concept (PoC) exploit is available on GitHub, including a shell script (POC.sh) that demonstrates the ANSI escape sequence injection via a crafted malicious filename (PoC Repository). As of the time of reporting, there is no evidence of in-the-wild exploitation, and the EPSS score is approximately 0.326%, indicating a low near-term exploitation probability (GitHub Advisory). The vulnerability is not listed in the CISA KEV catalog, and no threat actor attribution has been identified. Nessus detection (plugin 335310) is available for identifying vulnerable installations (Feedly).

1. Craft a malicious filename: Create a C/C++ source file (or directory) whose name embeds ANSI escape sequences, for example: touch $'\033[2K\033[1A\033[2K\033[1Amalicious.c'. This causes terminal control characters to be embedded in the filename.
2. Place the file in a target repository: Introduce the maliciously named file into a repository or directory that will be scanned by flawfinder — this could be via a pull request, a shared codebase, or a CI/CD pipeline input.
3. Trigger flawfinder scan: Wait for or cause a developer or automated pipeline to run flawfinder against the directory containing the malicious file, e.g., flawfinder ./target_directory.
4. Observe output manipulation: The ANSI escape sequences in the filename are rendered by the terminal, potentially overwriting or hiding preceding scan output lines, making it appear that no vulnerabilities were found.
5. Inject into structured reports (optional): If flawfinder is invoked with --csv or --sonarqube output options, the unsanitized filename or code context is written directly into the report, corrupting CSV structure or injecting arbitrary XML attributes into SonarQube output via output_sonar() (PoC Repository, GitHub Advisory).

• File System: Presence of files or directories with names containing non-printable characters or ANSI escape sequences (e.g., \033[, \x1b[) in repositories being scanned by flawfinder.
• Logs: Flawfinder terminal output or log files containing raw ANSI escape sequences (e.g., ESC[2K, ESC[1A) in filename fields, which may cause lines to be overwritten or hidden in terminal displays.
• Reports: CSV or SonarQube XML reports generated by flawfinder containing unexpected special characters, malformed XML attributes, or broken CSV field delimiters in filename or category columns.
• CI/CD Pipeline: Automated scan results that appear unexpectedly clean or truncated when scanning repositories with recently added files from untrusted contributors (GitHub Advisory, PoC Repository).

Upgrade Flawfinder to version 2.0.20 or later, which fully patches this vulnerability (released 2026-05-16). Users can upgrade via pip using pip install --upgrade flawfinder; GitHub Actions users should update their workflow to reference david-a-wheeler/flawfinder@2.0.20 or later. If an immediate upgrade is not possible, mitigate risk by pre-scanning filenames for control characters before passing them to flawfinder, reviewing raw output in a text editor that displays escape sequences, and avoiding generation of SonarQube or CSV reports from untrusted repositories (GitHub Advisory, Flawfinder Advisory).

Red Hat has tracked this vulnerability via their Bugzilla system (Bug 2514323) with a high severity rating, indicating it is being monitored for impact on Red Hat products (Red Hat Bugzilla). The initial filename injection issue was credited to security researcher Dan Lenz, with additional vulnerabilities discovered by the flawfinder project maintainer David A. Wheeler himself, who promptly issued the patch (Flawfinder Advisory). No significant broader media coverage or social media discussion has been identified beyond the advisory and PoC publication.