Security updates released for Exim Mail Transfer Agent (MTA) and addressed multiple possible remote-triggered critical vulnerabilitiesallowing RCE.
Theflaw affected outdated Exim deployments. It is a user-after-free (UAF) flaw triggered during the TLS shutdown while handling BDAT chunked SMTP traffic.
Exim is a widely used open-source mail transfer agent deployed across enterprise, ISP, academic, and government infrastructures for internet-connected Unix systems. CVE-2026-45185 was discovered and reported by XBOW researcher Federico Kirschbaum. It impacts Exim versions 4.97 through 4.99.2 on builds compiled with GnuTLS that have STARTTLS and CHUNKING advertised. OpenSSL-based builds are not affected.
The Exim Project has confirmed
All versions prior to 4.99.3 are obsolete.
Legacy 3.x versions are more than 20 years outdated and should no longer be used.
Version 4.99.3 is the latest security release addressing remotely triggerable issues.
The vulnerability impacts some Exim versions before 4.99.3 that use the default GNU Transport Layer Security (GnuTLS) library for secure communication. It is a user-after-free (UAF) flaw triggered during the TLS shutdown while handling BDAT chunked SMTP traffic.
There is a great deal of flexibility in the way mail can be routed, and there are extensive facilities for checking incoming mail. Exim can be installed in place of sendmail, although the configuration of Exim is quite different.
Vulnerability Exploitation
Attackers exploiting the vulnerability could execute commands on the server as well as access Exim data and emails, and potentially pivot further into the environment depending on server permissions and configuration.
Findings from EXBOW research:
XBOW Native successfully produced a working exploit for a simplified target Exim server that had no Address Space Layout Randomization (ASLR) and non-PIE (Position Independent Executables) binary.
In a second attempt, the LLM achieved an exploit on a machine with ASLR, but still a non-PIE binary.
“[…] instead of continuing to attack glibc’s allocator with off-the-shelf mechanisms, XBOW Native had taken on Exim’s own allocator,” XBOW researchers say.
Despite the surprising result below, it was the human researcher who won the race, with assistance from the LLM for tasks such as assembling files and testing exploitation avenues.
Threat actors commonly target internet-facing mail transfer agents due to their direct exposure to external networks and critical role in enterprise communication infrastructure.
Threat Context
Security Area
Details
Product
Exim Mail Transfer Agent (MTA)
Current Secure Version
4.99.3
Affected Versions
All versions prior to 4.99.3
Legacy Risk
Exim 3.x releases are obsolete
Attack Surface
Internet-facing SMTP services
Potential Impact
Remote exploitation, mail service compromise, unauthorized access
Indicators of Concern (IoCs / Risk Indicators)
Type
Indicator
Description
Network Activity
Unusual SMTP connections
Suspicious external mail interactions
Service Behaviour
Unexpected Exim crashes/restarts
Possible exploitation attempts
Log Activity
Unauthorized mail relay events
Potential abuse of mail routing
Authentication
Unknown SMTP authentication attempts
Credential abuse indicators
System Activity
Unexpected child process execution
Possible remote code execution attempts
Mitigations
Upgrade all Exim installations to version 4.99.3 immediately.
Identify and decommission obsolete Exim 3.x deployments.
Restrict unnecessary external exposure of SMTP services.
Audit mail server configurations and relay permissions.
For users of Ubuntu and Debian-based Linux distributions should apply the available Exim updates (v4.99.3) through their package managers.
Google Threat Intelligence Group (GTIG) has tracked and found how attackers have models pose as security researchers or firmware experts to perform analyses on embedded systems and protocols. The zeroday exploit set to target popular open-source web administration tool, generated using AI. Observations revealed hackers are deploying agentic tools to partially automate research and exploit validation.
This shifts AI from a passive assistant to a system that independently executes parts of offensive workflows.
Theis report provide insights derived from Mandiant incident response engagements, Gemini and GTIG’s proactive research. The highlights aim at the threat environment where AI serves dual purpose. On one hand to disrupt advance cyber threats from hackers and other AI tools acting as high value agents for cyber attacks.
Here are key highlights of the threat research:
Vulnerability Discovery and Exploit Generation: For the first time, GTIG has identified a threat actor using a zero-day exploit that we believe was developed with AI. The criminal threat actor planned to use it in a mass exploitation event but our proactive counter discovery may have prevented its use.
AI-Augmented Development for Defense Evasion: AI-driven coding has accelerated the development of infrastructure suites and polymorphic malware by adversaries. These AI-enabled development cycles facilitate defense evasion by enabling the creation of obfuscation networks and the integration of AI-generated decoy logic in malware that google have linked to suspected Russia-nexus threat actors.
Autonomous Malware Operations: AI-enabled malware, such as PROMPTSPY, signal a shift toward autonomous attack orchestration, where models interpret system states to dynamically generate commands and manipulate victim environments. Analysis of this malware revealed previously unreported capabilities and use cases for its integration with AI.
AI-Augmented Research and IO: Adversaries continue to leverage AI as a high speed research assistant for attack lifecycle support, while shifting toward agentic workflows to operationalize autonomous attack frameworks.
Obfuscated LLM Access: Threat actors now pursue anonymized, premium tier access to models through professionalized middleware and automated registration pipelines to illicitly bypass usage limits. This infrastructure enables large scale misuse of services while subsidizing operations through trial abuse and programmatic account cycling.
Supply Chain Attacks: Adversaries like “TeamPCP” (aka UNC6780) have begun targeting AI environments and software dependencies as an initial access vector. These supply chain attacks result in multiple types of machine learning (ML)-focused risks outlined in the Secure AI Framework (SAIF) taxonomy, namely Insecure Integrated Component (IIC) and Rogue Actions (RA).
Hackers leveraging AI for vulnerability development and Zeroday exploitation
Cybercriminal groups are increasingly leveraging AI to support vulnerability discovery and exploit development.
Google Researchers observed threat actors planning large-scale exploitation campaigns using AI-assisted techniques.
A zero-day vulnerability was identified in a Python script capable of bypassing Two-Factor Authentication (2FA) in a popular open-source web administration tool. The exploit required valid user credentials but bypassed 2FA due to a hardcoded trust assumption within the application logic. Analysis suggests the vulnerability discovery and exploit development were likely assisted by an AI model due to:
Structured and highly “textbook” Python coding style
Excessive educational docstrings
Hallucinated CVSS scoring
LLM-like formatting patterns and helper classes
Unlike traditional vulnerabilities such as memory corruption or input validation flaws, this issue was a high-level semantic logic flaw difficult for conventional scanners to detect. Frontier AI models are becoming increasingly capable of:
Understanding developer intent
Identifying hardcoded security assumptions
Detecting hidden logic inconsistencies
Surfacing vulnerabilities missed by static analysis and fuzzing tools
The incident highlights the growing risk of AI-assisted zero-day discovery and exploitation by threat actors and as AI use datasets containing historical vulnerabilities to help models better reason about security flaws.
“For the first time, GTIG has identified a threat actor using a zero-day exploit that we believe was developed with AI,” GTIG researchers say.
What can be the consequences specifically at a time when new AI models unlike Anthropic’s Mythos, which were announced last month and appear to be good at finding such holes that Anthropic shared.
Rob Joyce, the former cybersecurity director of the National Security Agency, said that it can be difficult to know whether a human or machine wrote computer code, adding that, “A.I.-authored code does not announce itself.”
The Zeroday Defect
The report’s main findings involves a zero-day exploit that GTIG assessed was likely developed with AI assistance.
The vulnerability affected a popular open-source, web-based system administration tool and allowed two-factor authentication to be bypassed, although valid user credentials were still required.
The zero-day flaw was detected by the Google Threat Intelligence Group within the past few months and was exploited by “prominent cybercrime threat actors” in a script of the Python programming language.
Allow hackers to bypass two-factor authentication on “a popular open-source, web-based system administration tool,” though the hackers also would have needed access to valid credentials like user names and passwords to be successful, the company said.
Malware Evasion Techniques via AI
Hackers are also leveraging malware evasion techniques and sandbox evasions and other tricks to stay out of sight. As defenders increasingly rely on AI to accelerate and improve threat detection, a subtle but alarming new contest has emerged between attackers and defenders.
GTIG identified several malware families or tools with LLM-enabled obfuscation features, including PROMPTFLUX, HONESTCUE, CANFAIL, and LONGSTREAM.
Here is an example:
In June 2025, a malware sample was anonymously uploaded to VirusTotal from the Netherlands. At first glance, it looked incomplete. Some parts of the code weren’t fully functional, and it printed system information that would usually be exfiltrated to an external server.
The sample contained several sandbox evasion techniques and included an embedded TOR client, but otherwise resembled a test run, a specialized component or an early-stage experiment. What stood out, however, was a string embedded in the code that appeared to be written for an AI, not a human. It was crafted with the intention of influencing automated, AI-driven analysis, not to deceive a human looking at the code.
The malware includes a hardcoded C++ string, visible in the code snippet below:
In-memory prompt injection.
Hackers can leverage these emerging AI Evasion techniques to bypass AI-powered security systems by manipulating how Large Language Models (LLMs) interpret, analyze, and classify malicious content or activity.
How Attackers May Use AI Evasion Techniques
Prompt Injection Attacks Attackers craft malicious inputs that manipulate AI models into ignoring security rules, revealing sensitive information, or executing unintended actions.
Bypassing AI-Based Detection Threat actors can design malware, phishing emails, or malicious scripts in ways that appear legitimate to AI-powered detection systems.
Manipulating Context & Intent AI systems rely heavily on context and language interpretation. Attackers may exploit ambiguous wording, hidden instructions, or layered prompts to confuse AI defenses.
Generating Adaptive Malware AI-generated malware can dynamically modify behavior, code structure, or communication patterns to evade traditional and AI-driven security tools.
Automating Social Engineering AI can help create highly convincing phishing messages, fake identities, and impersonation attempts that are harder for AI-based defenses to detect.
Conclusion: AI is significantly strengthening cybersecurity defenses.
Security teams are leveraging AI for real-time threat detection, behavioral analytics, automated incident response, vulnerability management, and proactive risk assessment. While attackers currently benefit from AI-driven automation and exploitation capabilities, defenders are expected to gain a stronger long-term advantage as AI evolves into a core component of secure software development, proactive cyber defense, and intelligent security operations.
Summary : Fluent Bit is a widely used opensource tool for collecting and forwarding logs in cloud and containers like Kubernetes environments. A chain of 5 critical vulnerabilities discovered by Oligo Security team and findings reveal that attackers can misuse via Remote code execution putting cloud and container at risk.
These vulnerabilities are CVE-2025-12977 CVE-2025-12970, CVE-2025-12969, CVE-2025-12978 , CVE-2025-12972. The vulnerabilities allow attackers to bypass authentication, manipulate log routing, achieve remote code execution, potentially leading to full compromise of cloud and Kubernetes environments using Fluent Bit for logging and observability.
Organizations relying on Fluent Bit must upgrade to the fixed versions and harden configurations to prevent remote takeover and log tampering.
Vulnerability Name
CVE ID
Product Affected
Severity
CVSS Score
Fixed Version
Fluent Bit Tag_Key Input Validation Bypass
CVE-2025-12977
Fluent Bit
Critical
9.1
v4.0.12+ , v4.1.1+ , v4.2.0+
Fluent Bit Docker Input Stack Buffer Overflow
CVE-2025-12970
Fluent Bit
High
8.8
v4.0.12+ , v4.1.1+ , v4.2.0+
Fluent Bit Forward Input Authentication Bypass
CVE-2025-12969
Fluent Bit
Medium
6.5
v4.0.12+ , v4.1.1+ , v4.2.0+
Fluent Bit Tag Spoofing via Partial Tag_Key Match
CVE-2025-12978
Fluent Bit
Medium
5.4
v4.0.12+ , v4.1.1+ , v4.2.0+
Fluent Bit File Output Path Traversal
CVE-2025-12972
Fluent Bit
Medium
5.3
v4.0.12+ , v4.1.1+ , v4.2.0+
Technical Summary
Fluent Bit vulnerabilities center around unsafe handling of tags and inputs, enabling attackers to manipulate routing, file paths and memory in ways that directly impact host systems and downstream security tooling.
These flaws can allow path traversal and arbitrary file writes, which in many real-world setups may escalate to remote code execution and persistent node compromise.
Additional vulnerabilities include stack buffer overflows and missing authentication checks that let attackers crash agents, execute code and inject false telemetry into trusted logging pipelines.
Source: Oligo.security
CVE ID
Vulnerability Details
Impact
CVE-2025-12977
Improper input validation allows injection of control chars, newlines, and path traversal sequences in tag values.
Log corruption and output injection.
CVE-2025-12970
Stack buffer overflow on container name copy due to lack of length check.
Partial string comparison on Tag_Key lets attacker spoof tags by guessing first char.
Manipulation of log routing and filtering.
CVE-2025-12972
Path traversal via unsanitized tags causes arbitrary file write and possible remote code execution.
Arbitrary file write and RCE.
Remediation:
Upgrade all Fluent Bit deployments to v4.2.0 / v4.1.1 / v4.0.12 or latest version.
Here are some recommendations below
Avoid using dynamic or untrusted tags in configuration for routing or file naming.
Always set explicit fixed Path or File parameters in out_file outputs to prevent path traversal.
Ensure forward inputs use both Shared_Key and Security.Users for proper authentication enforcement.
Limit network access to Fluent Bit instances to trusted sources only.
Run Fluent Bit with least privilege and restrict filesystem and configuration file write permissions.
Monitor logs and telemetry for abnormal tag values or unexpected log routing changes.
Conclusion: The Fluent Bit vulnerabilities enable attackers to hide activity, corrupt evidence and even gain direct control of cloud workloads.
This puts cloud systems at risk because security teams may not see the real activity happening inside their environment.
Organizations using Fluent Bit should patch immediately, restrict network access and enforcing strong authentication and least‑privilege deployment as urgent priorities to reduce the risk of remote takeover and systemic observability compromise.