--- title: Palo Alto Networks firewall zero-day exploited for... description: Palo Alto Networks has disclosed that suspected state-sponsored hackers have been actively exploiting CVE-2026-0300, a critical buffer overflow zero-day in... canonical: https://daily.dev/posts/palo-alto-networks-firewall-zero-day-exploited-for-nearly-a-month-mejdrqdqh twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Palo Alto Networks firewall zero-day exploited for nearly a month | daily.dev og:description: Palo Alto Networks has disclosed that suspected state-sponsored hackers have been actively exploiting CVE-2026-0300, a critical buffer overflow zero-day in... og:url: https://daily.dev/posts/palo-alto-networks-firewall-zero-day-exploited-for-nearly-a-month-mejdrqdqh og:image: https://api.daily.dev/og/posts/meJdRqDqH.png og:image:alt: Palo Alto Networks firewall zero-day exploited for nearly a month og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Palo Alto Networks firewall zero-day exploited for nearly a month **[BleepingComputer](https://daily.dev/sources/bleepingcomputer)** · 3 min read · 1 upvotes · 0 comments ## Summary Palo Alto Networks has disclosed that suspected state-sponsored hackers have been actively exploiting CVE-2026-0300, a critical buffer overflow zero-day in PAN-OS User-ID Authentication Portal (Captive Portal), since at least April 9, 2026. The flaw allows unauthenticated remote code execution with root privileges on internet-exposed PA-Series and VM-Series firewalls. After successful compromise, attackers deployed EarthWorm and ReverseSocks5 tunneling tools and performed log cleanup to evade detection. The threat cluster (CL-STA-1132) is linked to likely state-sponsored actors, with EarthWorm previously associated with Chinese APT groups including Volt Typhoon and APT41. Over 5,400 PAN-OS VM-series firewalls are exposed on the internet. Patches are expected May 13; until then, Palo Alto strongly advises restricting or disabling the Authentication Portal. CISA has added the CVE to its KEV catalog and ordered federal agencies to remediate by May 9. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Palo Alto Networks warns of firewall RCE zero-day exploited in attacks](https://daily.dev/posts/palo-alto-networks-warns-of-firewall-rce-zero-day-exploited-in-attacks-zo4m3vufc) · BleepingComputer · 3 upvotes · 0 comments - [Palo Alto's firewall OS has been under attack from multiple ransomware groups since June](https://daily.dev/posts/palo-alto-s-firewall-os-has-been-under-attack-from-multiple-ransomware-groups-since-june-jzzdv3s3y) · The Register · 0 upvotes · 0 comments - [Attackers exploit Palo Alto GlobalProtect flaw days after disclosure](https://daily.dev/posts/attackers-exploit-palo-alto-globalprotect-flaw-days-after-disclosure-7jl7oxcpm) · CSO Online · 0 upvotes · 0 comments --- Tags: [#zero-day](https://daily.dev/tags/zero-day) [View this post on daily.dev](https://daily.dev/posts/palo-alto-networks-firewall-zero-day-exploited-for-nearly-a-month-mejdrqdqh) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Palo Alto Networks firewall zero-day exploited for nearly a month","url":"https://daily.dev/posts/palo-alto-networks-firewall-zero-day-exploited-for-nearly-a-month-mejdrqdqh","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/palo-alto-networks-firewall-zero-day-exploited-for-nearly-a-month-mejdrqdqh"},"datePublished":"2026-05-07T10:58:30.420Z","dateModified":"2026-05-13T14:12:12.647Z","description":"Palo Alto Networks has disclosed that suspected state-sponsored hackers have been actively exploiting CVE-2026-0300, a critical buffer overflow zero-day in...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/37c771c972982ff12ff75ddcd26d127c?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/37c771c972982ff12ff75ddcd26d127c?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"BleepingComputer","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"BleepingComputer","logo":"https://media.daily.dev/image/upload/s--as8nJ3qy--/f_auto,q_auto/v1774959951/logos/bleepingcomputer?_a=BAMAMiWQ0","url":"https://daily.dev/sources/bleepingcomputer"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/palo-alto-networks-firewall-zero-day-exploited-for-nearly-a-month-mejdrqdqh","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"zero-day","timeRequired":"PT3M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"BleepingComputer","item":"https://daily.dev/sources/bleepingcomputer"},{"@type":"ListItem","position":3,"name":"Palo Alto Networks firewall zero-day exploited for nearly a month"}]} ```