CVE-2026-103820: 
NixOS 脆弱性の分析と軽減

CVE-2026-103820 is a path traversal vulnerability (CWE-22) affecting Adobe's CAI Content Credential ecosystem — specifically the Content Credentials Rust SDK, Content Credentials JS SDK, and C2PA Tool. The flaw allows an attacker to write arbitrary files to unauthorized locations outside of intended directory restrictions. Affected versions include Content Credentials Rust SDK up to and including c2pa-v0.90.15, Content Credentials JS SDK up to and including @contentauth/c2pa-web@0.13.4, and C2PA Tool up to and including c2patool-v0.27.15. The vulnerability was published on October 13, 2026, with patches released the same day. It carries a CVSS v3.1 base score of 5.5 (Medium) (GitHub Advisory, Adobe Advisory).

The vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), a classic "zip slip" or archive path traversal pattern. When a victim extracts a maliciously crafted archive file using one of the affected SDKs or tools, the software fails to properly sanitize file paths embedded within the archive, allowing path components such as ../ sequences to resolve to locations outside the intended extraction directory. The attack vector is local, requires no privileges, but does require user interaction — specifically, a victim must be tricked into extracting the malicious file. No public proof-of-concept code has been identified (GitHub Advisory, Adobe Advisory).

Successful exploitation results in arbitrary file writes to locations outside the intended extraction directory on the victim's file system, with a high integrity impact and no direct confidentiality or availability impact per the CVSS scoring. In practice, arbitrary file write primitives can be escalated to code execution by overwriting executable files, configuration files, startup scripts, or other sensitive system artifacts. The scope is limited to the local system of the user who extracts the malicious file, with no direct network-based lateral movement capability (GitHub Advisory, Adobe Advisory).

There is no evidence of active in-the-wild exploitation or publicly available proof-of-concept code as of the time of publication. The EPSS score is approximately 0.216% (11th percentile), indicating a low near-term exploitation probability. The NVD SSVC assessment classifies exploitation as "none" and the attack as non-automatable, reflecting the requirement for user interaction. CVE-2026-103820 does not appear in the CISA Known Exploited Vulnerabilities (KEV) catalog (GitHub Advisory, Adobe Advisory).

1. Craft malicious archive: Create an archive file (e.g., a C2PA-compatible container or supported archive format) with embedded file entries whose paths contain directory traversal sequences (e.g., ../../etc/cron.d/malicious or ../../.bashrc) pointing to sensitive locations outside the intended extraction directory.
2. Deliver the file: Distribute the maliciously crafted file to a target user via email, file sharing, or any social engineering vector, disguising it as a legitimate Content Credentials or C2PA asset.
3. Induce extraction: Convince the victim to open or extract the file using a vulnerable version of c2patool (≤0.27.15), the Rust SDK (≤c2pa-v0.90.15), or the JS SDK (≤@contentauth/c2pa-web@0.13.4).
4. Achieve arbitrary file write: The vulnerable extraction logic fails to sanitize traversal sequences, writing attacker-controlled content to the resolved out-of-bounds path on the victim's file system.
5. Escalate to code execution (optional): If the written file overwrites an executable, script, or configuration file that is subsequently executed (e.g., a shell profile, cron job, or application config), the attacker may achieve code execution in the context of the victim user (GitHub Advisory, Adobe Advisory).

• File System: Unexpected files appearing in directories outside the intended extraction path (e.g., home directory, /etc/, startup script directories, application config folders); modification timestamps on system files coinciding with archive extraction events.
• Logs: OS-level audit logs (e.g., Linux auditd, Windows Security Event Log) showing file creation or write events by c2patool or SDK processes in unexpected directories; application logs recording extraction of archives with unusual path entries.
• Process: c2patool or Node.js/Rust SDK processes writing files to paths containing .. sequences; unexpected child processes spawned after file extraction (indicative of overwritten scripts being executed).
• Network: Outbound connections from the victim host shortly after file extraction, potentially indicating a follow-on payload executed via an overwritten script (no specific network IOCs are confirmed for this CVE).

Adobe has released patched versions for all three affected components: Content Credentials Rust SDK v0.91.1 (fixing versions ≤c2pa-v0.90.15), C2PA Tool v0.28.1 (fixing versions ≤c2patool-v0.27.15), and Content Credentials JS SDK @contentauth/c2pa-web@0.15.3 (fixing versions ≤0.13.4). Users should update to these versions immediately. As a behavioral workaround, organizations should train users not to extract C2PA or Content Credential archives from untrusted or unknown sources. No configuration-based mitigation is available as a substitute for patching (Adobe Advisory, GitHub Advisory).

The vulnerability received routine coverage from automated security feeds and vulnerability tracking services, including AusCERT (ESB-2026.12622) and cve.report, as well as a Mastodon post from the @cve account on infosec.exchange. No notable independent researcher commentary or significant media coverage has been identified beyond standard advisory republication. Community sentiment appears measured given the medium severity score and requirement for user interaction.