KEV Lag Tracker → CVE-2025-25249. Data verified against the official CISA KEV catalog and the National Vulnerability Database.
CISA added CVE-2025-25249 (Fortinet Multiple Products) to the Known Exploited Vulnerabilities catalog on September 9, 2026. It was publicly known for 239 days before CISA confirmed active exploitation. A KEV listing is CISA’s official confirmation that a vulnerability is being exploited in the wild.
The Record
| CVE | CVE-2025-25249 |
| Vendor / product | Fortinet Multiple Products |
| Vulnerability | Fortinet Multiple Products Heap-based Buffer Overflow Vulnerability |
| CVSS base score | 8.1 |
| EPSS probability the day before the KEV listing | 0.76% (52.9% percentile) |
| NVD publication date | January 13, 2026 |
| Added to CISA KEV | September 9, 2026 |
| Lag (public → KEV listing) | 239 days |
| Federal patch deadline | September 12, 2026 |
| Known ransomware use | No |
Measured against the 1720 entries in our tracker with verified publication dates, CVE-2025-25249 was flagged faster than 50% of them.
What CISA Reported
CISA describes the flaw as follows: “Fortinet FortiOS, FortiSwitchManager, and FortiSASE contain a heap-based buffer overflow vulnerability that allows an attacker to execute unauthorized code or commands via specially crafted packets.”
Federal Patch Deadline
Under Binding Operational Directive rules, U.S. federal agencies must remediate CVE-2025-25249 by September 12, 2026 — a 3-day remediation window from the KEV listing date. Private organizations are not bound by that deadline; CISA treats it as the benchmark for how urgently a confirmed-exploited flaw should be patched.
What EPSS Forecast Before the Confirmation
The EPSS forecast (FIRST’s daily estimate of the probability a CVE will be exploited within 30 days) put CVE-2025-25249 at 0.76% on the day before CISA confirmed active exploitation — the 52.9% percentile of all scored CVEs that day. That places it outside the top 10% of EPSS risk on the eve of confirmation — a patch queue ordered by EPSS alone would have left it for later.
| EPSS for CVE-2025-25249 | Value |
|---|---|
| Probability the day before the KEV listing | 0.76% |
| Percentile the day before the KEV listing | 52.9% |
| Probability today (September 23, 2026) | 2.40% |
| Percentile today | 83.3% |
Today’s figure is not evidence that the forecast worked: EPSS reacts to the KEV listing itself, so the score for any confirmed-exploited CVE tends to rise after CISA acts. Only the eve-of-listing number was available to a defender making the call. Across every KEV entry we track, we measured how often that number was high — see the EPSS accuracy analysis.
How This Compares to Fortinet’s Track Record
At 239 days, CVE-2025-25249 was flagged slower than Fortinet’s 10-day median across the 30 of its KEV entries with verified publication dates.
| Fortinet in the CISA KEV catalog | Value |
|---|---|
| Tracked KEV entries | 30 |
| Median lag (public → KEV listing) | 10 days |
| 0-day rate (exploited at or before disclosure) | 33% |
| Entries tied to known ransomware campaigns | 13 |
Other Recent Fortinet KEV Additions
| CVE | Product | Added to KEV | Lag (days) | Ransomware |
|---|---|---|---|---|
| CVE-2025-68686 | FortiOS | July 27, 2026 | 167 | No |
| CVE-2026-25089 | FortiSandbox | July 16, 2026 | 37 | No |
| CVE-2026-39808 | FortiSandbox | July 16, 2026 | 93 | No |
| CVE-2026-21643 | FortiClient EMS | April 13, 2026 | 66 | No |
| CVE-2026-35616 | FortiClient EMS | April 6, 2026 | 2 | No |
Frequently Asked Questions
What is CVE-2025-25249?
CVE-2025-25249 is a vulnerability in Fortinet Multiple Products (Fortinet Multiple Products Heap-based Buffer Overflow Vulnerability) that CISA added to its Known Exploited Vulnerabilities catalog on September 9, 2026. A KEV listing is CISA’s official confirmation that the flaw is being exploited in the wild.
How long was CVE-2025-25249 public before CISA confirmed exploitation?
239 calendar days, measured from its NVD publication date to the date CISA added it to the KEV catalog.
What is the federal patch deadline for CVE-2025-25249?
U.S. federal agencies must remediate CVE-2025-25249 by September 12, 2026, a 3-day window from the KEV listing date. Private organizations are not bound by that deadline, but CISA treats it as the benchmark for how urgently a confirmed-exploited flaw should be patched.
Is CVE-2025-25249 used in ransomware campaigns?
CISA has not flagged CVE-2025-25249 as known to be used in ransomware campaigns. That field reflects confirmed campaign use, not the absence of risk.
What was the EPSS score for CVE-2025-25249 before it was confirmed as exploited?
0.76% — the probability EPSS assigned on the day before CISA added CVE-2025-25249 to the KEV catalog, placing it in the 52.9% percentile of all scored CVEs that day. That is outside the top 10% of EPSS risk. Its score today is higher in most cases because EPSS reacts to the KEV listing itself, so only the eve-of-listing figure reflects what a defender could have acted on.
How does this compare to other Fortinet vulnerabilities?
Across 30 Fortinet entries with verified publication dates, the median lag is 10 days and 33% were exploited at or before disclosure. CVE-2025-25249, at 239 days, is slower than that median.
Related Coverage
- Critical Microsoft SharePoint Flaw CVE-2026-50522 (CVSS 9.8) Added to CISA KEV (July 2026)
- WordPress’s CVE-2026-63030 Was Exploited in 4 Days — Well Under Its 420-Day Median (July 2026)
Primary Sources
- CISA Known Exploited Vulnerabilities Catalog — the official listing that confirms active exploitation, and the source of the KEV date on this page.
- NVD — CVE-2025-25249 — publication date, CVSS score and the full technical record.
- Vendor advisory — fortiguard.fortinet.com — Fortinet’s own disclosure, with the affected versions and the fix.
How We Track This
This page is generated from our CISA KEV Lag Tracker, which syncs the official CISA KEV catalog daily and records the date each CVE is added. For every entry we retrieve the original NVD publication date and compute the lag in calendar days. No date or figure on this page is estimated or taken from a third-party source — they come directly from CISA and NVD records. Free to cite with attribution to CVEDaily (CC BY 4.0).