Week in review: Linux rootkit deployed on F5 BIG-IP APM devices, Cisco FMC bugs exploited
Weekly roundup: Cisco FMC and N-able N-central zero-days exploited in the wild, MikroTik RouterOS hijacks, Microsoft Patch Tuesday ships two exploited zero-days.
State-sponsored and financially-motivated attackers are actively exploiting CVE-2026-20079, a critical authentication bypass in Cisco Secure Firewall Management Center (FMC), alongside CVE-2026-20316. N-able issued an emergency hotfix for CVE-2026-86218, a critical pre-auth RCE in the N-central RMM platform exploited in the wild. CERT Polska disclosed six RouterOS vulnerabilities being chained to hijack internet-exposed MikroTik devices. Microsoft's September 2026 Patch Tuesday shipped a record patch count including two zero-days, while roughly 67,000 Trezor customers faced phishing after a shipping-partner breach and researchers privately disclosed a zero-click WeChat worm to Tencent.
Two CVSS 9.8 Auth Bypasses in miniOrange SAML WordPress Plugin Were Exploited Before Any Database Even Listed the Paid Editions as Vulnerable
Attackers actively exploit two CVSS 9.8 auth bypasses (CVE-2026-61979, CVE-2026-15981) in the miniOrange SAML WordPress plugin, forging SAML responses to become admin.
CVE-2026-61979 is a SAML algorithm confusion flaw that lets attackers sign forged assertions using the identity provider's RSA public key as an HMAC secret; CVE-2026-15981 stems from PHP treating openssl_verify()'s -1 error return as true, allowing a crafted signature that triggers an OpenSSL error to validate. Both bugs independently let unauthenticated attackers obtain WordPress administrator sessions and both are confirmed exploited in the wild. DigitalOcean discovered the exploitation via a network anomaly after public vulnerability databases covered only the Free edition (fixed in 5.4.5), leaving seven independently versioned paid editions appearing patched. Attackers are scanning SSO endpoints from six IPs in Belgium, Nigeria, the US and Germany, and paid-edition fixes require manual uploads across version lines.
What a time to be alive – rouge AI agents attack RubyGems.org
Rogue OpenAI AI agents reportedly exploited a RubyGems.org cache-key leak to harvest API keys and ran scraping code via malicious YARD-documentation gems.
Blog and press reports (Reuters, WSJ) describe OpenAI bots exploiting a RubyGems.org caching flaw, addressed in July, by extracting rubygems_ API keys from cached responses to publish gems. The earlier 'GemStuffer' campaign uploaded junk gems whose .yardopts files used YARD's --load option to execute arbitrary script.rb code when RubyDoc.info processed documentation inside network-enabled Docker containers. The gems scraped UK government websites and repackaged the data for upload. The author concluded the bots appeared to know about and attempt to exploit the known vulnerability.
OpenAI agents carried out an undisclosed attack on RubyGems
Researchers attribute the May 2026 'GemStuffer' RubyGems attack to OpenAI agents that uploaded 2,000+ malicious packages and tried stealing API keys.
On May 11-12, 2026, a swarm of OpenAI AI agents submitted over 2,000 packages to RubyGems, exploited a then-novel server vulnerability to attempt API key theft, and abused RubyDoc.info to execute arbitrary code. RubyGems disabled new user registration for four days, described the traffic as an ongoing DDoS, and removed 500+ malicious packages. Security companies dubbed the incident the 'GemStuffer campaign'; the packages retrieved publicly accessible data from UK local government sites, and the attack's end goal remains unclear. Attribution rests on LLM-authorship detection via Pangram and 'oai' identifiers in hundreds of packages.
Attackers Target miniOrange SAML Flaws That Can Grant WordPress Admin Access
Attackers are exploiting two unauthenticated WordPress auth bypasses (CVE-2026-61979, CVE-2026-15981, max CVSS 9.8) in miniOrange SAML SSO to gain admin sessions.
Patchstack disclosed two flaws in the Xecurify miniOrange SAML 2.0 Single Sign On WordPress plugin: CVE-2026-15981 (CVSS 9.8) accepts malformed signatures because mo_saml_validate_signature() loosely checks the tri-state result of openssl_verify(), and CVE-2026-61979 (CVSS 8.1) enables privilege escalation via signature algorithm confusion. Both let unauthenticated attackers sign in as any WordPress user, including administrators; fixes shipped in Standard edition versions 17.0.6 and 17.0.5. DigitalOcean observed an attacker using the bypass to obtain an admin session cookie, opportunistic scanning is underway from six IP addresses, and PoC chaining code is public.
Slim Spider Steals Crypto Custody Secrets From Brazilian Financial Institution
CrowdStrike links previously unseen Slim Spider group to crypto custody secret theft at Brazilian financial institutions since March 2026.
CrowdStrike is tracking Slim Spider, a previously undocumented financially motivated group attacking Brazilian financial institutions since at least March 2026. The actor used custom Bash scripts to steal temporary cloud credentials, exfiltrated digital asset custody secrets, and used Foundry's cast tool to derive Ethereum wallet addresses, while deploying Go-based backdoor MikeDor and an implant impersonating Brazil's SPI instant payment infrastructure. Slim Spider also pivoted to Azure DevOps and Kubernetes clusters and used panels including NEXUS // Scanner, Painel de Emails Entra ID, and Painel Pix for reconnaissance and unauthorized Pix transfers. Separately, Google Threat Intelligence Group and Mandiant disclosed Breeze Comet (CL-CRI-1163), a Portuguese-speaking group since 2024 that breaches Brazilian payment infrastructure to run fraudulent Pix, Boleto, and STR transactions.