Actively exploited vulnerabilities in 2026: the October data, and how to triage them

About 80,000 CVEs were published in the first nine and a half months of 2026, more than twice as many as in the same period of 2025 (Empirical Security). Attackers exploited a sliver of them. Google's threat intelligence group puts the share of 2026 disclosures seen in active exploitation at 0.23%, roughly one in 431 (GTIG).

That sliver is what this report is about. We pulled CISA's Known Exploited Vulnerabilities catalog and FIRST's EPSS scores and computed what they say about 2026. We also ran a Valyu DeepResearch brief on every vulnerability exploited between 20 September and 23 October, fact-checked it against the primary sources, and published the result with its corrections. The data is free to download.

Published 23 October 2026. Data as of CISA KEV catalog version 2026.10.21 (1,754 entries). Refreshed monthly.

TL;DR

• Exploitation is rising, but far more slowly than disclosure. CVE publication has more than doubled this year. CISA's exploited list grew 30%: 270 additions to 20 October, already more than the 245 it added in all of 2025.
• The worst of it is at the edge. 15 of the 38 KEV additions between 21 September and 20 October were firewalls, VPNs, gateways and remote-access tools, and they top our patch list: Citrix NetScaler, BeyondTrust Remote Support, Ivanti Connect Secure, F5 BIG-IP APM, Check Point, Cisco and Arista.
• Several were zero-days for weeks. BeyondTrust was exploited from late August and Citrix from early September, well before patches. For these, patching is not enough: check for compromise.
• EPSS scored many of them low, even after the fact. 46% of the vulnerabilities CISA confirmed as exploited in 2026 still scored below 0.1 on 22 October, including the BeyondTrust, Citrix and Cisco SD-WAN zero-days.
• Download: every 2026 KEV addition as a CSV, plus the DeepResearch brief and its corrected CSV.

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Which vulnerabilities are being actively exploited right now?

CISA added 38 vulnerabilities to its Known Exploited Vulnerabilities catalog between 21 September and 20 October 2026. The most urgent are unauthenticated flaws in internet-facing edge and remote-access products. This is the "patch this week" list from our DeepResearch brief, ranked by exploitation evidence, exposure and blast radius. We checked every exploitation claim and fixed version in it against the vendor's advisory or the primary report.

Also exploited in the window: Palo Alto Networks PAN-OS CVE-2026-0322 and AhsayCBS CVE-2026-105133 and CVE-2026-105134 (all added to KEV on 14 October), Microsoft Windows Shell CVE-2026-96951 (13 October), Atlassian Data Center CVE-2026-21589 (15 October), Fortinet CVE-2025-61624 (16 October) and SharePoint CVE-2026-65660 (25 September). The full list is in the CSV below.

How many CVEs have been published in 2026 so far?

About 80,000, depending on the counter. The CVE List recorded 79,680 CVEs between 1 January and 13 October 2026, against 36,998 in the same window of 2025 (Empirical Security). That passes FIRST's mid-year forecast of about 66,000 for the whole of 2026 (FIRST) with more than two months to go. Monthly volume doubled during the year, from 5,045 disclosures in January to 10,740 in August (GTIG).

Some of the growth is real discovery and some is counting. Google notes that automated assignment in open-source projects inflates the baseline: CVEs describing the Linux kernel alone accounted for about 5,000 records between January and August, with no exploited zero-days among them. NVD enrichment has also fallen behind, so a large share of 2026 CVEs have no NVD severity score at all, which makes charts based on NVD severity misleading.

How many of those CVEs are actually exploited?

Very few, and we can measure it two ways. Google's threat intelligence group found 0.23% of 2026 disclosures in active exploitation. We got almost exactly the same answer from public data. FIRST's EPSS model had scored 77,944 CVEs with 2026 IDs by 22 October. Of those, 183 are in CISA's Known Exploited Vulnerabilities catalog: 0.235%.

Here is what the KEV feed itself shows for 2026, as of catalog version 2026.10.21:

• CISA added 270 vulnerabilities to KEV between 1 January and 20 October 2026, against 207 in the same period of 2025 (up 30%) and 245 in the whole of 2025.
• September was the busiest month, with 43 additions, against 16 in September 2025.
• Old bugs keep surfacing. 183 of the 270 additions (68%) are 2026 CVEs, but 49 (18%) are CVEs from 2024 or earlier that were only confirmed as exploited this year.
• Ransomware use is known for 27 of them (10%), against 12.7% of 2025's additions.
• Deadlines have collapsed. 142 of the 270 (53%) came with a three-day federal remediation deadline. That is mostly policy: since CISA's BOD 26-04 took effect on 10 June, 111 of 137 additions (81%) have had three days.

The vendors and weaknesses behind 2026's KEV additions:

The most common weaknesses were code injection (CWE-94, 19 entries), improper authentication (CWE-287, 17), OS command injection (CWE-78, 15), path traversal (CWE-22, 14), deserialization of untrusted data (CWE-502, 13) and missing authentication for a critical function (CWE-306, 12).

EPSS misses many of them. Of the 270 vulnerabilities CISA confirmed as exploited in 2026, 125 (46%) still had an EPSS score below 0.1 on 22 October, even after exploitation was known. Only 160 of all 77,944 scored 2026 CVEs (0.21%) score above 0.1.

• Download every 2026 KEV addition (270 rows: CVE, vendor, product, KEV dates, ransomware flag, CWEs, and EPSS score and percentile as of 22 October 2026).

What did the October 2026 Patch Tuesday fix, and why do the counts differ?

Microsoft's 13 October release fixed 1,408 CVEs by Microsoft's own count, more than the 1,244 it fixed in the whole of 2025 (Empirical Security). Trackers report between 1,407 and 1,415 for the same release because they treat Chromium-based Edge and third-party CVEs differently (BleepingComputer counted 1,411). Only one of them was exploited: CVE-2026-96951, a Windows Shell Mark of the Web bypass, which CISA added to KEV the same day. (BleepingComputer's count of three zero-days includes two that were publicly disclosed before the fix but not exploited.)

The lesson matches the year as a whole. A record count of fixes is not a record count of threats. One CVE out of more than 1,400 needed same-day attention.

How fast are attackers exploiting new vulnerabilities?

Fast, and often before the fix exists. The answer depends on what you measure, so these figures should not be merged:

The autumn's cases show the range. Check Point's gateway flaw was attacked three days after its fix shipped. BeyondTrust and Citrix NetScaler were exploited for weeks before anyone disclosed them. PHP2Shell attempts began four days before disclosure.

Which vendors have the most exploited vulnerabilities in 2026?

Microsoft, by a distance: 40 of 2026's 270 KEV additions, followed by Cisco (19), then Fortinet and Apple (9 each). The most dangerous ones sit at the network edge. Google found edge and security appliances made up 14% of the vulnerabilities it saw exploited in the first eight months of 2026, and more than 65% of those were rated high or critical (GTIG). In our window alone, Cisco disclosed exploited zero-days in both SD-WAN Manager and Secure Email Gateway, Citrix had three NetScaler CVEs added to KEV within a week, and Arista's VeloCloud Orchestrator had its third exploited flaw since July.

The bug classes repeat too: authentication bypass, path traversal, memory corruption and command injection. And fixes do not always close the exposure. Orchestrators that took Arista's July and September fixes were still affected by the October flaw (The Hacker News).

Is AI behind the surge in CVEs?

Partly, and it is hard to measure. No CVE field records how a bug was found. What the evidence does show:

• AI-found bugs skew severe. Google reports that 50% of AI-discovered vulnerabilities lead to remote code execution, against 26% across all CVEs (GTIG).
• Exploitation is rising too, but from a small base. Google recorded 141 exploited vulnerabilities in January to August 2026, already more than the 127 it recorded in all of 2025.
• Attackers use AI agents as well. In October, researchers documented an operator using an open-source AI agent platform against company websites: break-in attempts on more than 1,200 sites, roughly $5 per attack task and, by NorForge's own caveated estimate, about 10% of tasks reaching their goal (NorForge, The Hacker News). NorForge independently validated two compromises. Humans still picked the targets.
• AI tooling is now attack surface. CISA added 11 vulnerabilities in Langflow, LiteLLM, n8n, Ray and MLflow to KEV this year. MCP servers and coding agents logged hundreds of CVEs but no documented exploitation yet. We track them in every 2026 CVE in MCP servers, coding agents and LLM gateways.

The safe planning assumption: discovery is getting cheaper for everyone, and attackers will turn patches into exploits faster than before.

KEV, EPSS or CVSS: what should you patch first?

Patch on evidence of exploitation first, exposure second and severity third. In practice:

1. KEV, vendor-confirmed and credible threat-intelligence exploitation first. Include exploitation that has not reached KEV yet: Arista confirms CVE-2026-114625 is exploited, and it was not in KEV when this was written. Treat credible attempts as urgent too: PHP2Shell drew exploitation attempts from 17 October, with no confirmed compromise as of 22 October.
2. Do not gate on EPSS. On 22 October, EPSS scored the exploited BeyondTrust flaw at 0.0118, Citrix CVE-2026-88771 at 0.0108, the Cisco SD-WAN flaw at 0.0182 and the Windows Shell flaw at 0.0151 (FIRST EPSS). EPSS is useful for ranking the long tail, but it is a forecast, not a record: weeks after CISA confirmed exploitation, almost half of 2026's KEV additions still scored below 0.1.
3. Measure edge patching in hours, not days. For internet-facing appliances, the exploitation window is now shorter than most monthly patch cycles.
4. Pair patching with a compromise check. For NetScaler, CISA says to check for compromise before patching. For BeyondTrust, rebuild and rotate credentials. For Ivanti, reset the appliance on suspicion.
5. Use CVSS to break ties, not to set the queue.

How do you turn this list into a patch plan for your own stack?

Ask a narrower question: which of these touch what you run, and what do you do today? That is a research problem, and it is the one DeepResearch is built for.

We ran a single max-mode DeepResearch task on 23 October with this brief: every vulnerability exploited between 20 September and 23 October, which to patch first, and what 2026's CVE volume means for vulnerability management. It read 146 sources and returned a 4,200-word report with a 44-row CSV.

We then fact-checked it against the CISA KEV feed, NVD, FIRST EPSS and vendor advisories. Of 360 checks, 322 confirmed the report, 31 found an error (11 of them serious enough to change a patch decision) and 7 could not be verified. The headline figures and every row of the "patch this week" table held up. The errors were concentrated in the CSV's metadata. It marked five KEV-listed CVEs as not in KEV, left the KEV due date blank, and had four fixed versions wrong. The body also wrongly said Ivanti's 22.8 branch had no fix.

We think that is the honest picture of where AI research is today. It is excellent at reading 146 sources and finding the ten things that matter. It still needs a check against the primary record before anything goes into a change ticket. So the open-source cve-monitor tool now checks every CVE in its findings against CISA's KEV feed automatically.

• Read the full DeepResearch report (unedited output).
• Download the corrected CSV (44 vulnerabilities; KEV fields taken from CISA's feed and four fixed versions corrected after the fact-check).

Corrections to the unedited report:

1. The CSV marks five KEV-listed CVEs as not in KEV: PAN-OS CVE-2026-0322 and AhsayCBS CVE-2026-105133 and CVE-2026-105134 (added 14 October), MikroTik CVE-2026-67279 (added 25 September) and Oracle PeopleSoft CVE-2026-35273 (added 12 June, known ransomware use).
2. The kev_due_date column is empty. Use the KEV feed for due dates.
3. Citrix CVE-2026-88779 is fixed in 14.1-73.41 and 13.1-64.28. It was added to KEV on 4 October, not 27 September.
4. FortiOS CVE-2025-61624 is fixed in 7.6.5 and later and 7.4.10 and later. FortiOS 7.2, 7.0 and 6.4 have no fix and must be migrated (FG-IR-26-122).
5. Ivanti Connect Secure 22.8 does have a fix for CVE-2026-104935: 22.8R2.5.
6. BeyondTrust CVE-2026-102764 is fixed by patch BT26-05-RS for versions 24.3.1 to 26.2.3, not by a "26.2.4" release.

To run the same research every morning for your own stack, see how to automate CVE monitoring with AI, a cron job and Slack, or get it delivered with the hosted Slack and Microsoft Teams bots. If you would like help applying it to your environment, email contact@valyu.ai.

How was this data collected?

• KEV: the CISA Known Exploited Vulnerabilities JSON feed, catalog version 2026.10.21 (1,754 entries), downloaded on 23 October 2026.
• EPSS: FIRST's bulk EPSS scores for 22 October 2026 (model v2026.06.15), joined to KEV by CVE ID.
• CVE counts and other third-party figures: quoted with a link to the source named in the text. The CVE List, NVD and commercial trackers count differently, so we name each source rather than merging them.
• DeepResearch brief: one max-mode task created on 23 October 2026, published unedited, with the corrections listed above.

The datasets are released under CC BY 4.0: use them freely with attribution to Valyu. This page is refreshed monthly, after Patch Tuesday. Each refresh updates the tables and adds a changelog entry below.

Changelog

• 23 October 2026: first edition (KEV catalog 2026.10.21).

Frequently asked questions

What is the CISA Known Exploited Vulnerabilities catalog?

The KEV catalog is CISA's list of vulnerabilities with reliable evidence of exploitation in the wild. US federal civilian agencies must remediate entries by a set due date, and most security teams use it as their first priority list. CISA publishes it as a free JSON and CSV feed.

How many vulnerabilities are in CISA KEV?

As of catalog version 2026.10.21, released on 21 October 2026, the KEV catalog lists 1,754 vulnerabilities. CISA added 270 of them in 2026 up to 20 October, more than the 245 it added in all of 2025.

What is the difference between a zero-day and an actively exploited vulnerability?

A zero-day is exploited before the vendor has released a fix. An actively exploited vulnerability is being used in attacks, whether or not a fix exists. Every exploited zero-day is actively exploited, but most actively exploited vulnerabilities have had a patch available for some time.

How many CVEs did Microsoft fix in October 2026?

Microsoft's own count for the 13 October 2026 Patch Tuesday is 1,408 CVEs, more than it fixed in all of 2025. Other trackers count between 1,407 and 1,415. One of them, Windows Shell CVE-2026-96951, was exploited.

How many CVEs will be published in 2026?

FIRST's mid-year forecast was about 66,000, but publication passed that in October. The CVE List recorded 79,680 CVEs from 1 January to 13 October 2026, so the full-year total is likely to land well above 90,000.

What percentage of CVEs are ever exploited?

A small fraction. Google's threat intelligence group found that 0.23% of vulnerabilities disclosed in 2026 were observed in active exploitation, about one in 431.

Is EPSS better than CVSS for prioritising patches?

EPSS is better than CVSS at predicting which CVEs will be exploited, but neither should come first. Known exploitation does. On 22 October 2026, EPSS still scored several KEV-listed zero-days below 0.02, between six and 25 days after CISA listed them. EPSS estimates the chance of exploitation activity in the next 30 days. It is not a record of exploitation already confirmed.

How often is this report updated?

Monthly, shortly after Microsoft's Patch Tuesday. Each refresh updates the data and the tables, and the changelog records what changed.

Can I reuse this data?

Yes. The CSVs are released under CC BY 4.0, so you can use them for any purpose, including commercially, as long as you credit Valyu.