Heap-memory disclosure via invalid URL parsing
Published May 6, 2020 · Updated Aug 12, 2026
Information disclosure in Cisco ASA and FTD Software allows remote attackers to read device heap memory through the web services interface. The interface's URL parser mishandles buffer tracking for invalid URLs, causing crafted GET requests to return unintended heap contents. Exposure requires an affected AnyConnect IKEv2, AnyConnect SSL VPN, or clientless WebVPN configuration and can reveal cookies, usernames, email addresses, certificates, and heap addresses.
Summary
What happened
Information disclosure in Cisco ASA and FTD Software allows remote attackers to read device heap memory through the web services interface. The interface's URL parser mishandles buffer tracking for invalid URLs, causing crafted GET requests to return unintended heap contents. Exposure requires an affected AnyConnect IKEv2, AnyConnect SSL VPN, or clientless WebVPN configuration and can reveal cookies, usernames, email addresses, certificates, and heap addresses.
The record
- CVE
- CVE-2020-3259
- Published
- May 6, 2020
- Updated
- Aug 12, 2026
- Vendor
- ClamAV
- Product
- Cisco Adaptive Security Appliance (ASA) Software
- Classifications
- CWE-200, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 6, 2020CVE publishedPublication date reported by the CVE source.
- Aug 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=9.10 <9.10.1.40
- Affected versionversion=9.12 <9.12.3.9
- Affected versionversion=9.13 <9.13.1.10
- Affected versionversion=9.8 <9.8.4.20
- Affected versionversion=9.9 <9.9.2..67
- Affected versionversion=n/a
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- Cisco-observed attempted exploitationreported exploitation
- Akira ransomware exploitation of Cisco VPN servicesransomware
- CISA Known Exploited Vulnerabilities listingknown exploited catalog
Technologies
Your stack
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Your stack
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