Ransomware remains a serious network-security threat, but the latest federal advisories do not establish that the Medusa or Gunra campaigns used zero-day exploits. They describe ransomware activity involving stolen data, newly disclosed unpatched vulnerabilities, and other access methods. For defenders, the practical response is to reduce exposure, especially on internet-facing and unsupported systems, while ensuring the organization can restore from protected backups.
Here is what the current advisories establish, what they do not, and how to turn that information into priorities for network operations.
What do the current ransomware advisories say?
Two 2026 federal notices describe active ransomware threats. Both warn that the impact can extend beyond encrypted files: attackers may also steal information and threaten to publish it. That double-extortion pressure can create operational, legal, and reputational consequences even if an organization can restore its systems.
| Advisory | What it establishes | What it does not establish |
|---|---|---|
| Gunra ransomware notice, CISA and partner agencies, August 10, 2026 | Gunra actors use double extortion. The notice describes actors disabling backup features and an incident in which backup and archived data at primary and disaster-recovery centers were deleted. | The notice does not establish that Gunra used a zero-day exploit. |
| Medusa ransomware advisory update, CISA, FBI, and HHS, August 18, 2026 | Medusa uses double extortion. The advisory says the actors had impacted more than 500 victims across multiple critical-infrastructure sectors as of April 2026. It describes exploitation of newly disclosed, unpatched internet-facing vulnerabilities, along with other access methods. | The advisory does not establish that the exploited vulnerabilities were zero-days when used. |
The Medusa figure is a campaign-specific count reported in an August advisory with an April 2026 reference date. It is not a count of ransomware victims overall. Both notices are operational guidance, not evidence that every organization or sector faces the same level of exposure.
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How do ransomware groups get into networks?
Initial access is not limited to a single exploit. The Medusa advisory describes several routes and activity after entry:
- Exploitation of exposed vulnerabilities: Attackers may exploit internet-facing systems that have not been patched. A vulnerability being newly disclosed and unpatched does not, by itself, mean it was exploited as a zero-day.
- Phishing or access brokers: The advisory identifies phishing and brokers who sell or provide access as possible paths into victim networks.
- Legitimate utilities and remote-access tools: After gaining a foothold, attackers may use tools that administrators also rely on. The presence of a legitimate utility is not proof of an intrusion, so investigate its use in context, including account, source, timing, and destination.
After entry, ransomware operators may seek to move through the network, weaken defenses, interfere with backups, steal data, and encrypt systems. Restricting access between network segments and limiting who can reach remote services can make that progression harder.
Are current ransomware campaigns using zero-day exploits?
The cited 2026 advisories do not confirm that Medusa or Gunra used zero-days. The Medusa notice describes exploitation of newly disclosed vulnerabilities that were unpatched on internet-facing systems. That wording is not enough to conclude that attackers exploited a vulnerability before a fix or disclosure was available.
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A zero-day claim requires evidence about when the vulnerability was exploited relative to public disclosure or vendor availability of a fix. The current material supports a narrower conclusion: ransomware actors exploit vulnerable, exposed systems, including systems left unpatched after disclosure. The FBI’s 2026 cyber-alert index also warns that state actors exploit end-of-support edge devices, but that alert does not attribute this activity to either ransomware campaign.
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What should a network team prioritize?
Use the advisories to prioritize controls by exposure and consequence rather than treating every device or vulnerability as equally urgent.
- Identify internet-facing and unsupported assets. Inventory VPN gateways, remote desktop exposure, firewalls, routers, load balancers, and other edge systems. Mark firmware and software that is out of support. The FBI’s 2026 Cyber Alerts index identifies end-of-support load balancers, firewalls, routers, and VPN gateways as targets used by state actors for access and persistence.
- Prioritize known exploited vulnerabilities. Triage vulnerabilities affecting exposed systems, especially VPN gateways and infrastructure reachable through remote desktop services. Apply operating-system, application, and firmware updates within a risk-informed timeframe, as the Medusa advisory recommends. If an unsupported device cannot be patched, assess replacing it or isolating it from unnecessary access.
- Limit remote access and segment the network. Filter untrusted sources from internal remote services, restrict access to authorized users and systems, and separate critical systems from less-trusted parts of the network. Segmentation is intended to slow lateral movement; it does not remove the initial vulnerability or replace patching.
- Protect recovery copies from production compromise. Maintain offline, immutable backups in a physically separate, segmented location and test restoration. The Gunra notice describes backup-feature disruption and deleted backup and archived data at both primary and disaster-recovery centers, illustrating why a second copy that remains reachable from compromised systems may not be sufficient.
- Keep endpoint defenses and applications current. The FBI’s public ransomware guidance advises keeping systems and applications updated, updating anti-malware, and verifying regular backups, including disconnected copies.
For a control review or service comparison, ask whether the approach covers internet-facing assets and known exploited vulnerabilities; whether restoration from offline, immutable backups has been tested; how it limits remote access and lateral movement; and whether its operating model fits the organization, particularly if it supports critical infrastructure. These are decision criteria drawn from agency mitigations, not a ranking of vendors.
What should happen after a vulnerability is disclosed?
A disclosure is a cue to establish exposure and act, not just to add a ticket to a patch queue. Use a short, repeatable triage sequence:
- Find affected assets. Match the affected product and version against inventories, cloud and network records, and vendor-management data. Include externally reachable appliances and systems managed by service providers.
- Determine whether the vulnerable service is exposed. Confirm actual reachability and access controls rather than relying only on the device’s intended role.
- Assess exploitation and business impact. Check applicable known-exploited-vulnerability information and current agency advisories. Prioritize exposed assets whose compromise could enable access to critical services or backup infrastructure.
- Apply the available fix or reduce exposure. Patch or update firmware within a risk-informed timeframe. If that is not immediately possible, restrict access, disable unnecessary services where operationally safe, or isolate the system while planning remediation.
- Look for signs of compromise and verify recovery. Follow incident-specific indicators and response steps in current agency advisories. Confirm that protected backups remain available and that restoration procedures work.
If a vulnerability is suspected to be a zero-day, do not wait for a patch to reduce exposure. Follow vendor and agency instructions, restrict reachable services where feasible, and treat anomalous access as an incident requiring investigation. The evidence here does not identify a specific current ransomware zero-day, so teams should rely on advisories for the affected product rather than assume a particular campaign or exploit.
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How should an organization respond to a ransomware incident?
Once ransomware or related intrusion activity is suspected, use the current agency advisory for the relevant threat to guide incident-specific indicators and response. Preserve evidence and coordinate response through the organization’s incident-response process; avoid actions that could destroy logs or compromise the integrity of forensic evidence. Recovery plans should account for both encrypted systems and the possibility of data theft.
The FBI advises victims to contact a local FBI field office or report the incident to the Internet Crime Complaint Center (IC3). Its public ransomware guidance states: The FBI does not support paying a ransom in response to a ransomware attack.
It also cautions: Paying a ransom doesn’t guarantee you or your organization will get any data back.
That guidance is not a substitute for legal, regulatory, or incident-response advice specific to the organization. In particular, double extortion means that restoring files alone may not resolve the consequences of stolen data.
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The FBI’s current public ransomware guidance provides general prevention and reporting advice. CISA’s September 2023 #StopRansomware Guide is foundational material for broader preparation and response; it predates the 2026 activity described above, so use newer threat-specific advisories for current campaign details. CISA and partners’ June 2023 LockBit advisory is older context, not a substitute for current Medusa or Gunra guidance.
For current activity and incident-specific recommendations, consult the August 10, 2026 Gunra ransomware notice; the August 18, 2026 CISA, FBI, and HHS Medusa advisory update; and the FBI’s 2026 Cyber Alerts index. The FBI’s ransomware page is the source for its general prevention, reporting, and ransom-payment guidance.
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