Critical Memory corruption

CVE-2025-20363 — A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA)...

A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software, Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, remote attacker (Cisco ASA and FTD Software) or authenticated, remote attacker (Cisco IOS, IOS XE, and IOS XR Software) with low user privileges to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web service on an affected device after obtaining additional information about the system, overcoming exploit mitigations, or both. A successful exploit could allow the attacker to execute arbitrary code as root, which may lead to the complete compromise of the affected device. For more information about this vulnerability, see the Details ["#details"] section of this advisory.

Published Sep 25, 2025 · Updated Oct 18, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: cisco

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 6.9% (30-day exploitation probability)+14
Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

6.92%

ahead of 94% of scored CVEs · Oct 18, 2026

Affects

Cisco

Adaptive Security Appliance Software and 2 more

CVSS base

9.0

Critical · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Cisco Adaptive Security Appliance Software, Cisco Cisco Adaptive Security Appliance (ASA) Software, Cisco Cisco Firepower Threat Defense Software).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
EPSS ahead of 94% of scored CVEs: prioritize it in the patch queue.
Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Cisco	Adaptive Security Appliance Software	≥ 9.12 and < 9.12.4.72≥ 9.14 and < 9.14.4.28≥ 9.16 and < 9.16.4.84≥ 9.17.1 and < 9.18.4.57≥ 9.19.1 and < 9.19.1.42≥ 9.20.1 and < 9.20.3.16≥ 9.22 and < 9.22.2≥ 9.23 and < 9.23.1.3	Vulnerable	NIST National Vulnerability Database
Cisco	Cisco Adaptive Security Appliance (ASA) Software	version 9.17.1version 9.17.1.7version 9.17.1.9version 9.17.1.10version 9.17.1.11version 9.17.1.13version 9.17.1.15version 9.17.1.20 and 212 more version 9.17.1.30version 9.17.1.33version 9.17.1.39version 9.17.1.45version 9.17.1.46version 9.18.1version 9.18.1.3version 9.18.2version 9.18.2.5version 9.18.2.7version 9.18.2.8version 9.18.3version 9.18.3.39version 9.18.3.46version 9.18.3.53version 9.18.3.55version 9.18.3.56version 9.18.4version 9.18.4.5version 9.18.4.8version 9.18.4.22version 9.18.4.24version 9.18.4.29version 9.18.4.34version 9.18.4.40version 9.18.4.47version 9.18.4.50version 9.18.4.52version 9.18.4.53version 9.19.1version 9.19.1.5version 9.19.1.9version 9.19.1.12version 9.19.1.18version 9.19.1.22version 9.19.1.24version 9.19.1.27version 9.19.1.28version 9.19.1.31version 9.19.1.37version 9.19.1.38version 9.20.1version 9.20.1.5version 9.20.2version 9.20.2.10version 9.20.2.21version 9.20.2.22version 9.20.3version 9.20.3.4version 9.20.3.7version 9.20.3.9version 9.20.3.10version 9.20.3.13version 9.22.1.1version 9.22.1.3version 9.22.1.2version 9.22.1.6version 9.23.1version 9.8.4.32version 9.8.4.33version 9.8.4.34version 9.8.4.35version 9.8.4.39version 9.8.4.40version 9.8.4.41version 9.8.4.43version 9.8.4.44version 9.8.4.45version 9.8.4.46version 9.8.4.48version 9.12.1version 9.12.1.2version 9.12.1.3version 9.12.2version 9.12.2.4version 9.12.2.5version 9.12.2.9version 9.12.3version 9.12.3.2version 9.12.3.7version 9.12.4version 9.12.3.12version 9.12.3.9version 9.12.2.1version 9.12.4.2version 9.12.4.4version 9.12.4.7version 9.12.4.10version 9.12.4.13version 9.12.4.8version 9.12.4.18version 9.12.4.24version 9.12.4.26version 9.12.4.29version 9.12.4.30version 9.12.4.35version 9.12.4.37version 9.12.4.38version 9.12.4.39version 9.12.4.40version 9.12.4.41version 9.12.4.47version 9.12.4.48version 9.12.4.50version 9.12.4.52version 9.12.4.54version 9.12.4.55version 9.12.4.56version 9.12.4.58version 9.12.4.62version 9.12.4.65version 9.12.4.67version 9.14.1version 9.14.1.10version 9.14.1.6version 9.14.1.15version 9.14.1.19version 9.14.1.30version 9.14.2version 9.14.2.4version 9.14.2.8version 9.14.2.13version 9.14.2.15version 9.14.3version 9.14.3.1version 9.14.3.9version 9.14.3.11version 9.14.3.13version 9.14.3.18version 9.14.3.15version 9.14.4version 9.14.4.6version 9.14.4.7version 9.14.4.12version 9.14.4.13version 9.14.4.14version 9.14.4.15version 9.14.4.17version 9.14.4.22version 9.14.4.23version 9.14.4.24version 9.16.1version 9.16.1.28version 9.16.2version 9.16.2.3version 9.16.2.7version 9.16.2.11version 9.16.2.13version 9.16.2.14version 9.16.3version 9.16.3.3version 9.16.3.14version 9.16.3.15version 9.16.3.19version 9.16.3.23version 9.16.4version 9.16.4.9version 9.16.4.14version 9.16.4.18version 9.16.4.19version 9.16.4.27version 9.16.4.38version 9.16.4.39version 9.16.4.42version 9.16.4.48version 9.16.4.55version 9.16.4.57version 9.16.4.61version 9.16.4.62version 9.16.4.67version 9.16.4.70version 9.16.4.71version 9.16.4.76version 9.16.4.82version 9.8.1version 9.8.1.5version 9.8.1.7version 9.8.2version 9.8.2.8version 9.8.2.14version 9.8.2.15version 9.8.2.17version 9.8.2.20version 9.8.2.24version 9.8.2.26version 9.8.2.28version 9.8.2.33version 9.8.2.35version 9.8.2.38version 9.8.3.8version 9.8.3.11version 9.8.3.14version 9.8.3.16version 9.8.3.18version 9.8.3.21version 9.8.3version 9.8.3.26version 9.8.3.29version 9.8.4version 9.8.4.3version 9.8.4.7version 9.8.4.8version 9.8.4.10version 9.8.4.12version 9.8.4.15version 9.8.4.17version 9.8.2.45version 9.8.4.25version 9.8.4.20version 9.8.4.22version 9.8.4.26version 9.8.4.29	Vulnerable	CVE Program (cve.org) e CISA ADP
Cisco	Cisco Firepower Threat Defense Software	version 6.2.3version 6.2.3.1version 6.2.3.2version 6.2.3.3version 6.2.3.4version 6.2.3.5version 6.2.3.6version 6.2.3.7 and 64 more version 6.2.3.8version 6.2.3.10version 6.2.3.11version 6.2.3.9version 6.2.3.12version 6.2.3.13version 6.2.3.14version 6.2.3.15version 6.2.3.16version 6.2.3.17version 6.2.3.18version 6.6.0version 6.6.0.1version 6.6.1version 6.6.3version 6.6.4version 6.6.5version 6.6.5.1version 6.6.5.2version 6.6.7version 6.6.7.1version 6.6.7.2version 6.4.0version 6.4.0.1version 6.4.0.3version 6.4.0.2version 6.4.0.4version 6.4.0.5version 6.4.0.6version 6.4.0.7version 6.4.0.8version 6.4.0.9version 6.4.0.10version 6.4.0.11version 6.4.0.12version 6.4.0.13version 6.4.0.14version 6.4.0.15version 6.4.0.16version 6.4.0.17version 6.4.0.18version 7.0.0version 7.3.1version 7.2.4.1version 7.2.5version 7.2.5.1version 7.2.6version 7.2.7version 7.2.5.2version 7.2.8version 7.2.8.1version 7.2.9version 7.3.0version 7.0.1version 7.3.1.1version 7.3.1.2version 7.4.0version 7.4.1version 7.4.1.1version 7.4.2version 7.4.2.1version 7.4.2.2version 7.6.0version 7.7.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

High

Privileges required

None

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.0	CVSS 3.1	Critical	2.2	6.0	psirt@cisco.com via NIST National Vulnerability Database
9.0	CVSS 3.1	Critical	—	—	GitHub, Inc. via GitHub Security Advisories
9.0	CVSS 3.1	Critical	—	—	cisco via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-122 · Heap-based Buffer Overflow

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

2026
Affected products added · cisco/ios, cisco/cisco ios xr software, cisco/cisco adaptive security appliance (asa) software, cisco/cisco ios xe softw
Oct 18, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 18, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 18, 2026
Affected products added · cisco/ios xr, cisco/adaptive security appliance software, cisco/ios, cisco/ios xe, cisco/secure firewall threat defense
Oct 18, 2026 · NIST National Vulnerability Database
CVSS changed · 9.0
Oct 18, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 18, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 18, 2026 · Alertas do Telegram
2025
CVE published
Sep 25, 2025 · cisco

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 18, 2026 – Oct 18, 2026
1× Official description updated · Oct 18, 2026 – Oct 18, 2026

References

3 on the record

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-http-code-exec
Vendor Advisory, NIST National Vulnerability Database
github.com/advisories/GHSA-8wv4-73v4-qxp2
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2025-20363
GitHub Security Advisories

Elsewhere on this site

Cisco
every CVE for this vendor

Memory corruption
same class

CWE-122
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-20280 Cisco IOS XR Software Security Hardening Release: September 2026 Sep 2, 2026
High CVE-2026-20277 Cisco IOS XR Software Security Hardening Release: September 2026 Sep 2, 2026
High CVE-2026-20278 Cisco IOS XR Software Security Hardening Release: September 2026 Sep 2, 2026
Critical CVE-2026-20279 Cisco IOS XR Software Security Hardening Release: September 2026 Sep 2, 2026
High CVE-2026-20276 Cisco IOS XR Software Security Hardening Release: September 2026 Sep 2, 2026
Critical CVE-2026-20274 Cisco IOS XR Software Security Hardening Release: September 2026 Sep 2, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-20363 is "A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA)...", rated Critical. It affects Adaptive Security Appliance Software (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.0 describes technical severity. EPSS 6.92% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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