Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.54% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2025
CVE-2025-20244High confidence
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access VPN Web Server Denial of Service Vulnerability
Cisco · Cisco Adaptive Security Appliance (ASA) Software
Official source article: Cisco CISCO-SA-ASAFTD-VPNWEBS-DOS-HJBHMBSX ↗. Check the applicable product and release in the original source.
7.7HighCVSS 3.1
Within 7 days
Fix not verifiedHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Cisco Cisco Adaptive Security Appliance (ASA) Software and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Fix not verified01
What, why and how
A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow a remote attacker that is authenticated as a VPN user to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to incomplete error checking when parsing an HTTP header field value. An attacker could exploit this vulnerability by sending a crafted HTTP request to a targeted Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause a DoS condition, which would cause the affected device to reload.
What
A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow a remote attacker that is authenticated as a VPN user to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to incomplete error checking when parsing an HTTP header field value. An attacker could exploit this vulnerability by sending a crafted HTTP request to a targeted Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause a DoS condition, which would cause the affected device to reload.
Why
The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.
What
A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow a remote attacker that is authenticated as a VPN user to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to incomplete error checking when parsing an HTTP header field value. An attacker could exploit this vulnerability by sending a crafted HTTP request to a targeted Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause a DoS condition, which would cause the affected device to reload.
Why
The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may disrupt the affected service.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Validation of Specified Type of Input → disrupt the affected service
- Attack surface
- Network
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Changed: exploitation can affect a different security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-1287 ↗
CWE-1287: Improper Validation of Specified Type of Input. The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix not verified
- Affected
- Cisco Adaptive Security Appliance (ASA) Software: 9.12.3, 9.8.3, 9.12.1, 9.8.1, 9.12.2, 9.8.2.45, 9.8.2, 9.8.4, 9.14.1, 9.12.4, 9.8.2.26, 9.8.2.24, 9.8.2.15, 9.8.2.14, 9.8.2.35, 9.8.2.20, 9.8.2.8, 9.8.2.17, 9.8.2.28, 9.8.2.33, 9.8.2.38, 9.8.4.25, 9.12.3.2, 9.12.3.7, 9.8.3.18, 9.8.3.14, 9.8.4.15, 9.8.4.8, 9.8.1.7, 9.8.3.29, 9.14.1.10, 9.12.2.5, 9.8.4.22, 9.12.3.12, 9.8.4.7, 9.8.4.17, 9.8.3.16, 9.8.4.20, 9.8.3.11, 9.12.1.3, 9.8.4.3, 9.12.2.4, 9.8.4.12, 9.12.1.2, 9.8.3.26, 9.8.1.5, 9.12.2.9, 9.12.3.9, 9.8.3.21, 9.8.4.10, 9.12.2.1, 9.12.4.2, 9.14.1.6, 9.8.3.8, 9.14.1.15, 9.14.1.19, 9.8.4.26, 9.12.4.4, 9.14.1.30, 9.8.4.29, 9.12.4.7, 9.14.2, 9.12.4.8, 9.8.4.32, 9.12.4.10, 9.14.2.4, 9.14.2.8, 9.12.4.13, 9.8.4.33, 9.14.2.13, 9.8.4.34, 9.12.4.18, 9.8.4.35, 9.14.2.15, 9.12.4.24, 9.16.1, 9.8.4.39, 9.14.3, 9.12.4.26, 9.16.1.28, 9.14.3.1, 9.12.4.29, 9.14.3.9, 9.16.2, 9.12.4.30, 9.16.2.3, 9.8.4.40, 9.14.3.11, 9.12.4.35, 9.8.4.41, 9.14.3.13, 9.16.2.7, 9.12.4.37, 9.14.3.15, 9.17.1, 9.16.2.11, 9.14.3.18, 9.16.2.13, 9.12.4.39, 9.12.4.38, 9.8.4.43, 9.14.4, 9.16.2.14, 9.17.1.7, 9.12.4.40, 9.16.3.3, 9.14.4.6, 9.16.3, 9.16.3.14, 9.17.1.9, 9.14.4.7, 9.12.4.41, 9.17.1.10, 9.8.4.44, 9.18.1, 9.12.4.47, 9.14.4.12, 9.16.3.15, 9.18.1.3, 9.17.1.11, 9.12.4.48, 9.14.4.13, 9.18.2, 9.16.3.19, 9.17.1.13, 9.12.4.50, 9.14.4.14, 9.17.1.15, 9.8.4.45, 9.12.4.52, 9.14.4.15, 9.16.3.23, 9.18.2.5, 9.16.4, 9.12.4.54, 9.14.4.17, 9.8.4.46, 9.17.1.20, 9.18.2.7, 9.19.1, 9.16.4.9, 9.12.4.55, 9.18.2.8, 9.14.4.22, 9.16.4.14, 9.8.4.48, 9.18.3, 9.19.1.5, 9.14.4.23, 9.12.4.56, 9.16.4.18, 9.17.1.30, 9.19.1.9, 9.18.3.39, 9.16.4.19, 9.12.4.58, 9.19.1.12, 9.18.3.46, 9.16.4.27, 9.19.1.18, 9.18.3.53, 9.18.3.55, 9.16.4.38, 9.17.1.33, 9.12.4.62, 9.16.4.39, 9.18.3.56, 9.20.1, 9.16.4.42, 9.19.1.22, 9.18.4, 9.20.1.5, 9.18.4.5, 9.19.1.24, 9.16.4.48, 9.18.4.8, 9.20.2, 9.19.1.27, 9.12.4.65, 9.16.4.55, 9.18.4.22, 9.20.2.10, 9.16.4.57, 9.19.1.28, 9.17.1.39, 9.12.4.67, 9.14.4.24, 9.18.4.24, 9.20.2.21, 9.16.4.61, 9.19.1.31, 9.18.4.29, 9.20.2.22, 9.16.4.62, 9.18.4.34, 9.20.3, 9.16.4.67, 9.16.4.70, 9.18.4.40, 9.22.1.1, 9.16.4.71, 9.20.3.4, 9.16.4.76, 9.22.1.2, 9.16.4.82
- Cisco Firepower Threat Defense Software: 6.2.3.14, 6.4.0.1, 6.2.3.7, 6.2.3, 6.4.0.2, 6.2.3.9, 6.2.3.1, 6.2.3.2, 6.4.0.5, 6.2.3.10, 6.4.0, 6.4.0.3, 6.2.3.6, 6.4.0.4, 6.2.3.15, 6.2.3.5, 6.2.3.4, 6.2.3.3, 6.2.3.8, 6.4.0.6, 6.2.3.11, 6.2.3.12, 6.2.3.13, 6.4.0.7, 6.4.0.8, 6.6.0, 6.4.0.9, 6.2.3.16, 6.6.0.1, 6.6.1, 6.4.0.10, 6.4.0.11, 6.6.3, 6.6.4, 6.4.0.12, 7.0.0, 6.2.3.17, 7.0.0.1, 6.6.5, 7.0.1, 7.1.0, 6.4.0.13, 6.6.5.1, 6.2.3.18, 7.0.1.1, 6.4.0.14, 7.1.0.1, 6.6.5.2, 7.0.2, 6.4.0.15, 7.2.0, 7.0.2.1, 7.0.3, 6.6.7, 7.1.0.2, 7.2.0.1, 7.0.4, 7.2.1, 7.0.5, 6.4.0.16, 7.3.0, 7.2.2, 7.2.3, 6.6.7.1, 7.3.1, 7.1.0.3, 7.2.4, 7.0.6, 7.2.5, 7.2.4.1, 7.3.1.1, 7.4.0, 6.4.0.17, 7.0.6.1, 7.2.5.1, 7.4.1, 7.2.6, 7.0.6.2, 7.4.1.1, 6.6.7.2, 6.4.0.18, 7.2.7, 7.2.5.2, 7.3.1.2, 7.2.8, 7.6.0, 7.4.2, 7.2.8.1, 7.0.6.3, 7.4.2.1, 7.0.7, 7.4.2.2, 7.4.2.3
- Fixed
- No fixed version is explicitly recorded in the structured CVE data.
- Action
- No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 14 Aug 2025 · Last source change 14 Aug 2025, 19:19 UTC · CWE-1287 · Improper Validation of Specified Type of Input
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2025-24844
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.