Cisco Secure Firewall Adaptive Security…: Memory Allocation with Excessive Size Value
CVE-2024-20260 is a high-severity memory allocation with excessive size value vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software from Cisco, with a CVSS 3.1 base score of 8.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Cisco Secure Firewall Adaptive Security Appliance (ASA) Software versions: 9.16.1; 9.16.1.28; 9.16.2, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.6% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.1; 9.16.1.28; 9.16.2; 9.16.2.3; 9.16.2.7; 9.16.2.11; 9.16.2.13; 9.16.2.14; and 32 more ranges | Not stated |
| Cisco | Cisco Secure Firewall Threat Defense (FTD) Software | 7.0.0; 7.0.0.1; 7.0.1; 7.0.1.1; 7.0.2; 7.2.0; 7.0.2.1; 7.0.3; and 32 more ranges | Not stated |
| Cisco | firepower_threat_defense_software | 6.2.3 through 6.2.3.18; 7.4.1 through 7.4.1.1; 7.3.0 through 7.3.1.2; 7.2.0 through 7.2.8.1; 7.1.0 through 7.1.0.3; 7.0.0 through 7.0.6.2; 6.7.0 through 6.7.0.3; 6.6.0 through 6.6.7.2; and 1 more ranges | Not stated |
| Cisco | adaptive_security_appliance_software | 9.8.1 through 9.8.4.48; 9.20.2 through 9.20.2.21; 9.19.1 through 9.19.1.31; 9.18.1 through 9.18.4.29; 9.17.1 through 19.17.1.39; 9.16.1 through 9.16.4.61; 9.15.1 through 9.15.1.21; 9.14.1 through 9.14.4.24; and 1 more ranges | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H. Scored by CNA (cisco.com).
Official description
Update for September 16, 2026: The original 1.0 version of this advisory was specific to the Cisco Adaptive Security Virtual Appliance (ASAv) and Cisco Secure Firewall Threat Defense Virtual (FTDv) models. However, it was later found that this vulnerability affects all Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software platforms. A vulnerability in the VPN and management web servers of the Cisco Secure Firewall ASA Software and Cisco Secure FTD Software platforms could allow an unauthenticated, remote attacker to cause an affected device to run out of system memory or buffer blocks, which in turn could cause SSL VPN connection processing to slow down and eventually cease altogether. This vulnerability is due to a lack of proper memory management for new incoming SSL/TLS connections. An attacker could exploit this vulnerability by sending a large number of new incoming SSL/TLS connections to the targeted device. A successful exploit could allow the attacker to deplete system memory or buffers, resulting in a denial of service (DoS) condition. The memory or buffers could be reclaimed slowly if the attack traffic is stopped, but a manual reload may be required to restore operations quickly.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Memory Allocation with Excessive Size Value
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
How developers prevent this class of flaw
- Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.
- Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.
More Memory Allocation with Excessive Size Value vulnerabilities (CWE-789)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
- 8.6 High severity
- 8.8 High severity
- 8.1 High severity
- 8.4 High severity
- 8.8 High severity
- 9.9 Critical severity
Recent Memory Allocation with Excessive Size Value vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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