Last updated: August 19, 2026 at 1:47 AM UTC
All 741 Vulnerability 286 Breach 129 Threat 319 Defense 7
Tag: unpatched (12 articles)Clear

Unpatched Adobe Reader zero-day exploited since December - malicious PDFs steal data with zero clicks

An unpatched zero-day in Adobe Acrobat Reader has been actively exploited since at least November 2025 using booby-trapped PDF documents. The exploit, discovered by EXPMON researcher Haifei Li, works on the latest version of Adobe Reader without any user interaction beyond opening the file. It abuses privileged Acrobat JavaScript APIs (util.readFileIntoStream and RSS.addFeed) to silently harvest local files, OS details, language settings, and the Reader version from the victim's machine, then sends everything to an attacker-controlled server. The PDFs use Russian-language lures related to the oil and gas industry. The attack is a two-stage operation: the first pass fingerprints the target, and if the system meets the attacker's criteria, a follow-on RCE or sandbox escape payload is delivered. Only 5 out of 64 antivirus engines on VirusTotal detected the sample. No CVE has been assigned and no patch is available.

Check
Warn staff not to open PDF attachments from unknown or unexpected sources until Adobe releases a patch. This is especially urgent because the exploit requires no interaction beyond opening the file.
Affected
All current versions of Adobe Acrobat Reader on Windows and macOS. The exploit was confirmed working on Adobe Reader version 26.00121367, the latest at time of discovery.
Fix
No patch available yet - Adobe has been notified but has not released a fix. Immediate mitigations: disable JavaScript in Adobe Reader (Edit > Preferences > JavaScript > uncheck 'Enable Acrobat JavaScript'). Block outbound HTTP/HTTPS traffic containing 'Adobe Synchronizer' in the User-Agent header. Block the known C2 IP 169.40.2.68 on port 45191. Consider switching to an alternative PDF reader (like Foxit or browser-based viewing) until Adobe patches.

Unpatched Windows zero-day "BlueHammer" leaked after researcher's dispute with Microsoft - exploit code public, no fix available

A frustrated security researcher published working exploit code for an unpatched Windows local privilege escalation flaw after Microsoft's Security Response Center mishandled the disclosure. The researcher, posting as Chaotic Eclipse, dropped the proof-of-concept on GitHub on April 3 with the message "I was not bluffing Microsoft." Will Dormann of Tharsos confirmed the exploit works - it combines a TOCTOU race condition with path confusion to access the SAM database containing local account password hashes, enabling escalation to SYSTEM privileges. The exploit is confirmed working on Windows desktop but unreliable on Windows Server. The researcher deliberately included bugs in the PoC, but the underlying technique is now public and weaponizable.

Check
Assess your Windows endpoint fleet's exposure. This is a local privilege escalation - it requires an attacker to already have local access, making it a post-compromise escalation tool.
Affected
Windows desktop systems (Windows 10, Windows 11). Windows Server appears less affected - testing shows the exploit is unreliable on Server editions. No CVE has been assigned yet.
Fix
No patch available - this is an unpatched zero-day. Mitigate by restricting local user permissions to minimum necessary, monitoring EDR for unusual privilege escalation and SAM database access attempts, and hardening against the initial access vectors (phishing, stolen credentials) that would give attackers the local foothold they need. Watch for a Microsoft patch in an upcoming Patch Tuesday or out-of-band update.