CVE-2026-20100· NVD / CVE Program· CNA cisco

A vulnerability in the LUA interperter of the Remote Access SSL VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Softw

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.30% (FIRST EPSS).
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.
According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A vulnerability in the LUA interperter of the Remote Access SSL VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker with a valid VPN connection to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This does not affect the management or MUS interfaces. This vulnerability is due to trusting user input without validation in the LUA interprerter. An attacker could exploit this vulnerability by sending crafted HTTP packets to the Remote Access SSL VPN server. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

HighCVSS 7.7 · v3.1—No exploit No fix recorded

Published: Mar 4, 2026
Updated: Aug 11, 2026
EPSS: 0.3% · 21th percentile
CWE: CWE-120

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.7 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.3%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · cisco: 7.7; 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.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

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 software9.12.1
cisco adaptive security appliance software9.12.1.2
cisco adaptive security appliance software9.12.1.3
cisco adaptive security appliance software9.12.2
cisco adaptive security appliance software9.12.2.1
cisco adaptive security appliance software9.12.2.4
cisco adaptive security appliance software9.12.2.5
cisco adaptive security appliance software9.12.2.9
cisco adaptive security appliance software9.12.3
cisco adaptive security appliance software9.12.3.12
cisco adaptive security appliance software9.12.3.2
cisco adaptive security appliance software9.12.3.7
cisco adaptive security appliance software9.12.3.9
cisco adaptive security appliance software9.12.4
cisco adaptive security appliance software9.12.4.10
cisco adaptive security appliance software9.12.4.13
cisco adaptive security appliance software9.12.4.18
cisco adaptive security appliance software9.12.4.2
cisco adaptive security appliance software9.12.4.24
cisco adaptive security appliance software9.12.4.26

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
- 9.12.1, 9.12.1.2, 9.12.1.3, 9.12.2, 9.12.2.4, 9.12.2.5, 9.12.2.9, 9.12.3, 9.12.3.2, 9.12.3.7, 9.12.4, 9.12.3.12 … (+28)affected
Cisco Cisco Secure Firewall Threat Defense (FTD) Software
- 6.4.0, 6.4.0.1, 6.4.0.3, 6.4.0.2, 6.4.0.4, 6.4.0.5, 6.4.0.6, 6.4.0.7, 6.4.0.8, 6.4.0.9, 6.4.0.10, 6.4.0.11 … (+28)affected

Same product

cisco: all records

Other 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 FTKEV
90Now
CVE-2025-20333A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat DKEV
90Now
CVE-2020-3452Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Read-Only Path Traversal VulnerabilityKEV
90Now

Published before and after this one in the same product

← EarlierCVE-2026-20073Mar 4, 2026 · Cisco Secure Firewall Adaptive Security Appliance Software and Cisco Secure Firewall Threat Defense Software Access Control List Bypass Vulnerability
23Monitor
← EarlierCVE-2026-20082Mar 4, 2026 · A vulnerability in the handling of the embryonic connection limits in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software could
34Monitor
Later →CVE-2026-20101Mar 4, 2026 · A vulnerability in the SAML 2.0 single sign-on (SSO) feature of Cisco Secure Firewall ASA Software and Secure FTD Software could allow an un
34Monitor

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

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

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.

No dated events beyond publication.

EPSS, last 120 days

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 researchers

Finders, 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-2025-20333160 days apartA vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat DKEV
90Now

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

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: none
Integrity: none
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: None
Integrity impact: None
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:N/I:N/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 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1char buf[256];
2memcpy(buf, pkt->data, pkt->len);

Fixed

1char buf[256];
2if (pkt->len > sizeof(buf)) {
3  return -EINVAL;
4}
5memcpy(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)

ATT&CK techniques

—

Change 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-vpn-m9sx6MbC

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records