CVE-2026-15168: 
Wireshark vulnerability analysis and mitigation

CVE-2026-15168 is an information disclosure vulnerability in the BLF (Binary Logging Format) file parser of Wireshark, caused by use of an uninitialized variable (CWE-457). It affects Wireshark versions 4.6.0 through 4.6.6 and 4.4.0 through 4.4.16. The vulnerability was published on July 8, 2026, with patches released the following day. It carries a CVSS v3.1 base score of 3.3 (Low) per NVD, or 2.5 (Low) per ENISA/GitHub Advisory, reflecting its local, user-interaction-required attack vector (GitHub Advisory, Wireshark Advisory, Red Hat Bugzilla).

The root cause is classified under CWE-457 (Use of Uninitialized Variable) and CWE-237 (Improper Handling of Structural Elements), meaning the BLF file parser reads from heap memory that has not been properly initialized before use. An attacker crafts a malicious BLF file that, when parsed by Wireshark or tshark, causes the parser to expose uninitialized heap memory contents. Exploitation requires local access and user interaction — specifically, a victim must open the crafted BLF file. A public proof-of-concept Python script (generate_blf.py) exists that generates trigger files, with reproduction steps using MALLOC_PERTURB_=170 tshark -n -x -r trigger_zlib_oversize.blf to demonstrate the memory disclosure (Wireshark GitLab, GitHub Advisory).

Successful exploitation results in partial confidentiality loss through disclosure of uninitialized heap memory contents to an attacker who can supply a malicious BLF file to a victim. There is no impact on integrity or availability. The scope of impact is limited to the local system running the vulnerable Wireshark instance, and lateral movement potential is negligible given the constrained attack vector (GitHub Advisory, Red Hat Bugzilla).

1. Craft malicious BLF file: Use the public Python PoC script (generate_blf.py) from the Wireshark GitLab issue to generate a specially crafted BLF (Binary Logging Format) file designed to trigger the uninitialized heap memory read in the parser.
2. Deliver the file to the victim: Social-engineer or otherwise deliver the malicious .blf file to a target user who has a vulnerable version of Wireshark (4.4.0–4.4.16 or 4.6.0–4.6.6) installed.
3. Trigger parsing: The victim opens the crafted BLF file in Wireshark's GUI or processes it via tshark (e.g., MALLOC_PERTURB_=170 tshark -n -x -r trigger_zlib_oversize.blf), causing the BLF parser to read uninitialized heap memory.
4. Observe memory disclosure: The uninitialized memory contents are included in the parsed output, potentially exposing sensitive data from the victim's process heap (Wireshark GitLab).

• File System: Presence of unexpected or unsolicited .blf files delivered via email, file share, or download, particularly files with unusual sizes or structures that fail normal BLF validation.
• Process: Wireshark or tshark processes consuming unexpected memory or producing anomalous output when parsing BLF files; use of MALLOC_PERTURB_ environment variable in tshark invocations.
• Logs: Application crash logs or error output from Wireshark/tshark referencing BLF parser failures or zlib-related errors when processing specific files.

Wireshark has released patched versions 4.4.17 and 4.6.7 that address this vulnerability. Users should upgrade to one of these versions immediately. As a workaround prior to patching, avoid opening BLF files from untrusted or unknown sources, and restrict file-opening permissions to trusted users only (Wireshark Advisory, GitHub Advisory).

Red Hat has tracked this vulnerability via Bugzilla (Bug 2498329) and assigned it a low severity rating, with the bug filed against their Security Response product component. Linux distribution maintainers, including Fedora, have issued updated packages incorporating the fix, and coverage has appeared on Linux security news sites noting the broader Wireshark 4.6.7/4.4.17 security release addressing multiple CVEs (Red Hat Bugzilla).