SonicWall customers are attempting to dodge another security challenge as attackers are exploiting a pair of zero-day vulnerabilities that have been confirmed by the vendor. 

The company publicly disclosed the vulnerabilities — CVE-2026-15409 and CVE-2026-15410 — in a security advisory Tuesday. SonicWall credited an employee with discovering the defects, but it hasn’t said when the discovery occurred or the earliest known instance of exploitation. 

Rapid7 researchers told CyberScoop both vulnerabilities were first exploited June 22. “From the cases that our team has observed, the goal is likely ransomware, though we have prevented the actors from achieving exfiltration and encryption,” said Seth Lazarus, senior manager of detection and response services at Rapid7.

Overlapping tactics, techniques and procedures from the attacks observed by Rapid7 indicate the same threat group or attacker discovered and exploited the zero-days, Lazarus added.

SonicWall did not answer questions about the impacts of these attacks thus far, and the company hasn’t attributed the attacks to a known group or described the attacker’s origins and motivations.

The vendor did, however, confirm to CyberScoop that both vulnerabilities have been chained together for exploitation. The vulnerabilities affecting SonicWall SMA1000 appliances, including a max-severity defect that allows attackers to make authenticated requests and a 7.2-rated vulnerability that allows authenticated command injection.

“When these two are chained, an attacker can go from zero access to a complete system compromise for the affected appliance,” said Landon Rice, senior exploit developer at VulnCheck.

Ben Harris, founder and CEO at watchTowr, said two characteristics of the vulnerabilities fuel a sense of dread. “Both were exploited as zero-days before fixes were available, and together they offer a plausible path to remote-code execution from the internet,” he said.

The Cybersecurity and Infrastructure Security Agency added both zero-days to its known exploited vulnerabilities catalog Tuesday. 

SonicWall encouraged customers to patch the vulnerabilities by upgrading to the latest software version, which it released upon disclosure, and shared some indicators of compromise to help customers hunt for potential malicious activity on their systems.

“Speed of response was a priority for us,” said Bret Fitzgerald, senior director of global communications at SonicWall. “Within days of becoming aware of the issue, our team had developed a script that we can run on behalf of affected customers to assist with resolution, and mitigation efforts are already underway.”

SonicWall and third-party researchers haven’t said how many SonicWall customers are impacted by the exploited vulnerabilities, but the vendor did say it already investigated multiple cases of active exploitation. 

Fitzgerald said the company monitors about one million sensors globally and “SMA1000 appliances represent a very small subset of that footprint, less than 5,000 units.”

SonicWall said support staff are also helping customers work through instances of suspicious activity, warning that patching alone is not sufficient. 

The vendor and its customers have been hit by a barrage of actively exploited zero-days and previously disclosed defects in SonicWall devices for years. In 2025, an undisclosed state-sponsored threat actor intruded the company’s cloud environment and stole firewall configurations of every SonicWall customer. 

Seventeen defects affecting the vendor’s products have been added to CISA’s known exploited vulnerabilities catalog since late 2021. Ten of those defects are known to be used in ransomware campaigns, according to CISA, including a wave of about 40 Akira ransomware attacks between mid-July and early August.

“As always,” Harris said, “when something is confirmed as already exploited in the wild, patching is the bare minimum, and breach should be assumed.”

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Researchers and threat hunters are scrambling to respond to an actively exploited authentication-bypass vulnerability affecting Palo Alto Networks customers’ firewalls. 

The company initially tagged CVE-2026-0257 with a medium-severity rating when it disclosed the defect May 13, but quickly reassessed it as critical after Rapid7 observed and confirmed active exploitation in the wild. The Cybersecurity and Infrastructure Security Agency followed suit, and added the vulnerability to its known exploited vulnerabilities catalog Friday.

The escalated threat posed by the defect, which allows remote attackers to bypass security restrictions and establish a VPN connection to an affected firewall, showcases how quickly a seemingly mild vulnerability can turn into an urgent warning. 

“Palo Alto Networks is actively monitoring limited exploitation attempts targeting CVE-2026-0257 on unpatched PAN-OS devices where mitigations have not been applied,” a company spokesperson said in a statement. The company on Friday urged all customers to immediately apply the patch or follow its recommended steps for mitigation. 

The vendor and Rapid7, which first observed exploitation May 17 in a customer environment, declined to say how many organizations are impacted thus far. Yet, Douglas McKee, director of vulnerability intelligence at Rapid7, warned: “We’ve continued to see new victims roll in, including a couple of customers hit within just an hour of each other during a second wave of activity” on May 21. 

Jake Knott, security researcher at watchTowr, told CyberScoop the vulnerability and resulting exploits follows a recurring trend wherein attackers target exposed network edge devices and rapidly identify, develop and weaponize exploits for initial access. 

“This is yet another authentication bypass on a device whose sole job is to guard the front door to an organization’s network,” he said. “What stands out is how simple it is — an attacker can forge a valid authentication cookie using nothing more than the appliance’s publicly available TLS certificate. The entire exploit is a single HTTP request.”

The vulnerability has a few requisites that limit exposure, specifically posing risk to some Palo Alto Networks customers running GlobalProtect portal or gateway configured to enable authentication override cookies. 

“The cookie encryption and decryption certificate must be reused with another feature, which potentially exposes the public key for that certificate,” said Caitlin Condon, vice president of security research at VulnCheck.

“It’s difficult to say how many deployments meet those criteria for exploitability, but Palo Alto Networks firewalls have a very large footprint, which means even uncommon configurations can present significant attack surface area,” she added.

Rapid7 said the same attacker or group is likely responsible for both waves of exploitation last month, but in many cases attackers are not establishing a full VPN connection or moving to other parts of the impacted network. 

The attackers are “highly opportunistic and clearly monitor the security research community,” McKee said. “Attackers are purposefully weaponizing medium-severity vulnerabilities, which are typically lower priority or blind spots for organizations.”

Multiple threat clusters are swarming to the opportunity and quickly adapting to published research.  Researchers have not attributed the malicious activity to any specific threat groups. 

“Their exact origins and long-term objectives remain unclear, as they currently seem focused purely on opportunistic initial access rather than targeted, long-term espionage,” McKee said. 

Palo Alto Networks said it discovered the vulnerability internally through its use of frontier AI tools. Yet, within days of its public disclosure, initial assessments were proven inadequate.

“This is a pattern we continue to see — the urgency only arrives after exploitation is underway,” Knott said. “Organizations that wait for confirmation of active exploitation before patching will consistently find themselves reacting too late.”

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Congress wants answers from the Cybersecurity and Infrastructure Security Agency about the reported public exposure of sensitive agency credential data on GitHub in an incident that the security researcher who discovered it called one of the worst leaks he’s ever seen.

Other security professionals also voiced concern Tuesday about the leak and the potential for abuse by any malicious parties who got a hold of the information.

Security firm GitGuardian said it discovered a public GitHub repository last week that exposed credentials for privileged AWS GovCloud accounts and internal CISA systems dating back to November. The repository, apparently maintained by a contractor, was named “Private-CISA.” 

Krebs on Security first reported the incident.

“My main fear … is that a state actor will get the data and might be able to do bad stuff,” GitGuardian security researcher Guillaume Valadon told CyberScoop that he thought to himself upon discovering the leak, after concluding it was real; he initially thought it looked fake.

State-based attackers who obtained the credentials “might be able to gain persistence,” Valadon said, “so for me it’s even worse than an attacker destroying everything, having someone in a governmental system — it’s really, really bad.”

A House Homeland Security Committee aide said the panel is seeking a staff-level briefing from CISA on the matter.

Mississippi Rep. Bennie Thompson, the top Democrat on the Homeland Security Committee, and Delia Ramirez, the top Democrat on the panel’s cyber subcommittee, had separately demanded a briefing Tuesday in a letter to CISA’s acting director, Nick Andersen. 

They said they wanted to learn “how this serious security lapse occurred, any potential security consequences, remediation activities, corrective actions related to the contractor personnel involved, and efforts to monitor for and prevent similar activity from occurring in the future.”

Sen. Maggie Hassan, D-N.H., also sent a letter Tuesday to Andersen, seeking a classified briefing to answer questions about which systems were exposed, what forensic work CISA did to evaluate potential damage and what corrective action it has taken.

“This reported incident raises serious questions about how such a security lapse could occur at the very agency charged with helping to prevent cyber breaches,” Hassan wrote in the missive first reported by Axios, particularly “regarding CISA’s internal policies and procedures at a time of significant cybersecurity threats against U.S. critical infrastructure.”

Both letters pointed to personnel and budget cutbacks at the agency as a potential contributor to the incident.

CISA said it was looking into what happened.

“The Cybersecurity and Infrastructure Security Agency is aware of the reported exposure and is continuing to investigate the situation,” a spokesperson said. “Currently, there is no indication that any sensitive data was compromised as a result of this incident. While we hold our team members to the highest standards of integrity and operational awareness, we are working to ensure additional safeguards are implemented to prevent future occurrences.” 

The repository was reportedly maintained by a contractor at Nightwing. A Nightwing spokesperson referred questions to CISA.

The kind of exposure that happened for CISA “is an unfortunately painful, but common and repeated, if not relentless, way that we see organizations inadvertently leak very sensitive credentials to the wider web,” said Ben Harris, founder of WatchTowr, a company that helps organizations detect such exposures.

Harris told CyberScoop he didn’t want to speculate on what attackers who obtained the credentials might be able to do with it, but he said that it would be “terrifying” if the contractor was transferring information from work to home, as one researcher theorized.

Dave Mitchell, senior director of threat intelligence at Infoblox, told CyberScoop the incident showed the importance of teams having controls and audits in place across their repositories.

“Of all the things that keep me up at night, misconfigurations in GitHub are a recurring nightmare. It’s critical for so many organizations — all it takes is one accidental upload or misconfiguration and you’ve signed yourself up for a major incident,” he said in a written statement. “No need for a threat actor to use advanced techniques to compromise you if the keys are already sitting on the counter.”

Travis Rosiek, public sector chief technology officer at Rubrik, noted that the timing of the issue aligned with the government shutdown that only recently resolved for DHS. He said the incident showed the federal government needs to prioritize resilience.

“A persistent shortage of cybersecurity talent, combined with funding lapses, high workforce turnover, and an increasingly complex threat landscape, created the perfect storm for this scenario,” he said in a written statement to CyberScoop. “No organization is immune, and we must ensure that the federal government, which is responsible for helping protect the nation’s critical infrastructure and enhancing our cybersecurity posture, remains fully operational 24-7, 365 days a year.”

Without minimizing the severity of the incident, some researchers who have looked at the leak said there are mitigating circumstances that make elements of it defensible or, at least, understandable.

CISA acted very swiftly to remove the repository, Valadon said, once he alerted them to the leak.

And even if CISA has the right policies in place, human error still can make it difficult to entirely avoid incidents like this, Harris said.

“The reality is this happens every single day to different organizations, including cybersecurity companies,” he said, noting it would be different if it was a pattern. “This is not exclusive to CISA. I don’t really think it reflects well if we saw this every single day with CISA. … It’s not ideal that it’s even happened once, but the reality is that cybersecurity is people, process, technology.”

CISA has had other security incidents in the past, including recently. The former acting director of the agency endured criticism for uploading sensitive contract data to ChatGPT last year. In 2024 the agency notified Congress of a breach of a chemical plant security tool.

Updated 5/20/26: to include more information on a House Homeland Security Committee briefing request.

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Attackers are actively exploiting a zero-day vulnerability affecting some Palo Alto Networks’ customers’ firewalls, the security vendor said in an advisory Tuesday.

The critical memory corruption vulnerability — CVE-2026-0300 — affects the authentication portal of PAN-OS, and allows unauthenticated attackers to run  code with root privileges on the vendor’s PA-Series and VM-Series firewalls, the company said.

Palo Alto Networks did not say when or how it became aware of active exploitation, nor when the earliest known exploitation occurred. The Cybersecurity and Infrastructure Security Agency added the defect to its known exploited vulnerabilities catalog Wednesday.

The company hasn’t released a patch for the vulnerability or described the scope and objective of confirmed attacks.

“This vulnerability is specific to a limited number of customers with their User-ID Authentication Portal (Captive Portal) exposed to the public internet or untrusted IP addresses. We have observed limited exploitation of this issue and are working to release software fixes, with the first updates expected to be available on May 13,” a Palo Alto Networks spokesperson told CyberScoop.

The company said firewalls exposed to the buffer-overflow vulnerability, which has a CVSS rating of 9.3, are broadly exposed in real-world deployments, and it described the attack complexity as low.

Shadowserver scans found more than 5,800 publicly exposed VM-Series firewalls running PAN-OS as of Tuesday, yet it’s unknown how many of those instances have restricted authentication access to trusted internal IP addresses or disabled the feature altogether.

“We have provided clear mitigation guidance to our customers to secure their environments immediately. This issue does not impact Cloud NGFW or Panorama appliances. We remain committed to a transparent, security-first approach to protect our global customer base,” Palo Alto Networks’ spokesperson added.

Benjamin Harris, CEO and founder of watchTowr, noted that Palo Alto Networks proactively alerted customers to the zero-day, a step that allowed defenders to take action on potentially exposed instances. 

“In a bad situation, that is the best they can do immediately. However, that also alerts everyone to the existence of a vulnerability,” he told CyberScoop.

Despite the risk, Harris said watchTowr expects attacks linked to the zero-day exploit to be “very limited.” 

Palo Alto Networks and its impacted customers remain the only parties to have observed exploitation in the wild, but researchers warn that will likely change soon. 

“It’s likely rules will also start to fire in third-party organizations and honeypots shortly,” Caitlin Condon, vice president of security research at VulnCheck, told CyberScoop. 

“Management interfaces, login pages, and authentication portals have been common adversary targets for both opportunistic and targeted campaigns in recent years,” she added. “With researcher and community eyes on the vulnerability, it’s likely that we’ll see public exploits and broader exploitation quickly, provided the issue isn’t prohibitively difficult to exploit.”

Palo Alto Networks has yet to attribute the attacks to any known threat group, publish indicators or compromise, nor disclose the type of organizations that have been targeted and impacted. 

Researchers are hunting for malicious activity and advise customers to apply patches upon release.

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