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Fencer Vulns
high 7.7

CVE-2019-12677 json

Cisco Adaptive Security Appliance Software SSL VPN Denial of Service Vulnerability

published 2019-10-02 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-4268

cvss
7.7
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

A vulnerability in the Secure Sockets Layer (SSL) VPN feature of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition that prevents the creation of new SSL/Transport Layer Security (TLS) connections to an affected device. The vulnerability is due to incorrect handling of Base64-encoded strings. An attacker could exploit this vulnerability by opening many SSL VPN sessions to an affected device. The attacker would need to have valid user credentials on the affected device to exploit this vulnerability. A successful exploit could allow the attacker to overwrite a special system memory location, which will eventually result in memory allocation errors for new SSL/TLS sessions to the device, preventing successful establishment of these sessions. A reload of the device is required to recover from this condition. Established SSL/TLS connections to the device and SSL/TLS connections through the device are not affected. Note: Although this vulnerability is in the SSL VPN feature, successful exploitation of this vulnerability would affect all new SSL/TLS sessions to the device, including management sessions.

Patch / fix

  • cisco adaptive_security_appliance_software 9.1.7.4, 9.2.4.8, 9.3.3.9, 9.4.2.11, 9.5.2.5, 9.6.2

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
23 mo ago

Exploit prediction

1.53% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.0 7.7 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:N/A:P

Affected products

  • Cisco Cisco Adaptive Security Appliance (ASA) Software

Classification

Weakness
  • CWE-172 Improper Encoding or Decoding of Data
  • CWE-755 Improper Handling of Exceptional Conditions

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.