A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat D
A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP(S) requests. An attacker with valid VPN user credentials could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as root, possibly resulting in the complete compromise of the affected device.
- Published
- Sep 25, 2025
- Updated
- Aug 11, 2026
- EPSS
- 70.7% · 99th percentile
- CWE
- CWE-120
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Report tools
Action score
90
Now
Patch today or shut off access.
- CVSS
- 39 / 40 · 9.9 / 10
- CISA KEV
- 30 / 30 · Listed
- EPSS
- 21 / 30 · 70.7%
CISA SSVC decision
- Exploitation
- active
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · cisco
- 9.9
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Actively exploited in the wild
CISA added this to its Known Exploited Vulnerabilities catalog on Sep 25, 2025. That signals real attacks, not theory.
Remediation deadline for government agencies: Sep 26, 2025.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| cisco | adaptive security appliance software | cpe:2.3:o:cisco:adaptive_security_appliance_software |
| cisco | secure firewall threat defense | cpe:2.3:a:cisco:secure_firewall_threat_defense |
Using adaptive security appliance software? Add it to your stack and be the first to know about CVEs like this one. (Firewall)
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- cisco adaptive security appliance software9.12 and later · before 9.12.4.72
- cisco adaptive security appliance software9.14 and later · before 9.14.4.28
- cisco adaptive security appliance software9.16 and later · before 9.16.4.85
- cisco adaptive security appliance software9.17.0 and later · before 9.17.1.45
- cisco adaptive security appliance software9.18 and later · before 9.18.4.47
- cisco adaptive security appliance software9.19 and later · before 9.19.1.37
- cisco adaptive security appliance software9.20 and later · before 9.20.3.7
- cisco adaptive security appliance software9.22 and later · before 9.22.1.3
Versions reported by the vendor
Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
- 9.8.1, 9.8.1.5, 9.8.1.7, 9.8.2, 9.8.2.8, 9.8.2.14, 9.8.2.15, 9.8.2.17, 9.8.2.20, 9.8.2.24, 9.8.2.26, 9.8.2.28 … (+28)affected
Cisco Cisco Secure Firewall Threat Defense (FTD) Software
- 6.2.3, 6.2.3.1, 6.2.3.2, 6.2.3.3, 6.2.3.4, 6.2.3.5, 6.2.3.6, 6.2.3.7, 6.2.3.8, 6.2.3.10, 6.2.3.11, 6.2.3.9 … (+28)affected
Same product
cisco: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-20362Update: On November 5, 2025, Cisco became aware of a new attack variant against devices running Cisco Secure ASA Software or Cisco Secure FTKEV90Now
- CVE-2020-3452Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Read-Only Path Traversal VulnerabilityKEV90Now
- CVE-2018-0296A vulnerability in the web interface of the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to causeKEV90Now
- CVE-2024-20353A vulnerability in the management and VPN web servers for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat DefensKEV85Now
- CVE-2023-20269A vulnerability in the remote access VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTDKEV74This week
- CVE-2016-6367Cisco Adaptive Security Appliance (ASA) Software before 8.4(1) on ASA 5500, ASA 5500-X, PIX, and FWSM devices allows local users to gain priKEV68This week
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Proof-of-concept repository on GitHub ×3
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:0 | 2026-05-16 |
| Proof-of-concept repository on GitHub | stars:0 | 2026-08-22 |
| Proof-of-concept repository on GitHub | stars:0 | 2026-08-31 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- CISA KEV-1 d
- Published
- First PoC+232 d
- TodaySep 29, 2026+369 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-20100160 days apartA vulnerability in the LUA interperter of the Remote Access SSL VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Softw30Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
- CVE-2026-20009160 days apartCisco Secure Firewall Adaptive Security Appliance SSH Partial Private Key Authentication Bypass Vulnerability21Monitor
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
nvd-secondary
Root cause
When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.
The bug in code
The whole CWE-120 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
char buf[256];memcpy(buf, pkt->data, pkt->len);Fixed
char buf[256];if (pkt->len > sizeof(buf)) { return -EINVAL;}memcpy(buf, pkt->data, pkt->len);Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
- Overflow Variables and TagsCAPEC-46likelihood: High · High
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUB
- sec.cloudapps.cisco.com/security/center/resources/asa_ftd_continued_attacks
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20333
Vendor advisories and official records. Exploit/PoC links are deliberately left out.