CVE-2020-3259
A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to retrieve memory contents on an affected device, which could lead to the disclosure of confidential information. The vulnerability is due to a buffer tracking issue when the software parses invalid URLs that are requested from the web services interface. An attacker could exploit this vulnerability by sending a crafted GET request to the web services interface. A successful exploit could allow the attacker to retrieve memory contents, which could lead to the disclosure of confidential information. Note: This vulnerability affects only specific AnyConnect and WebVPN configurations. For more information, see the Vulnerable Products section.
- CVSS
- 7.5Highscored by the publisher (CNA)
- Exploited in the wild
- Yes, in CISA KEV since 15 Feb 2024CISA deadline for US federal agencies: 7 Mar 2024known use in ransomware campaigns
- EPSS
- 71.5%chance of exploitation in the next 30 daystop 0.6% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 6 May 2020analysed here 12 Nov 2026
Do first. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. (CISA's required action for this KEV entry)
Summary
Triage
- Attack surface
- Server-side
- Exploitable
- At runtime
- Attack vector
- network
- Weakness
- CWE-200 Information Exposure
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
Products named in our analysis
- cisco:secure_firewall_threat_defense
- cisco:adaptive_security_appliance_software
Fix and mitigation
WAF and other mitigations
Can a WAF block it? Partly. The attack involves sending specially crafted HTTP GET requests with invalid URLs to the device's web services interface, which a WAF can detect by matching unusual URL patterns that normal users do not generate. A WAF rule can match crafted GET requests with invalid URL syntax to the web services interface. No tracked WAF vendor has published a rule for this CVE yet, so you would write it yourself.
What a custom rule would match: crafted GET requests with invalid URL syntax to the web services interface
Also consider: patch · custom WAF rule · response filtering
Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Listed since 15 Feb 2024. Known use in ransomware campaigns.
- CISA due date
- 7 Mar 2024, the remediation deadline for US federal agencies
- CISA required action
- Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- Public exploit code
- None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
- CISA SSVC
- exploitation active, automatable yes, technical impact partialAssessed by CISA 14 Feb 2024 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
Timeline
- 6 May 2020Published
- 14 Feb 2024CISA SSVC assessment: exploitation active1,378 days (about 4 years) later
- 15 Feb 2024Added to CISA KEV (exploited in the wild)1 day later
- 7 Mar 2024CISA remediation due date (US federal agencies)21 days later
- 12 Aug 2026CVE record last updated888 days (about 2 years) later
- 12 Nov 2026Analysed by vulneraibility.com92 days (about 3 months) later
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
| Metric | Value | What it means |
|---|---|---|
| Attack vector | NetworkReachable over the internet or any routable network. | Reachable over the internet or any routable network. |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | NoneThe attacker needs no prior access. | The attacker needs no prior access. |
| User interaction | NoneNo victim action needed. | No victim action needed. |
| Scope | UnchangedImpact stays within the vulnerable component. | Impact stays within the vulnerable component. |
| Confidentiality | HighTotal data disclosure possible. | Total data disclosure possible. |
| Integrity | NoneNo unauthorised modification. | No unauthorised modification. |
| Availability | NoneThe service stays up. | The service stays up. |
Common questions
Is CVE-2020-3259 being exploited?
Yes. CVE-2020-3259 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2020-3259?
CVE-2020-3259 is rated High with a CVSS score of 7.5. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2020-3259?
Yes. A fix has been recorded for CVE-2020-3259. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2020-3259 affect?
CVE-2020-3259 affects cisco:secure_firewall_threat_defense, cisco:adaptive_security_appliance_software. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
2 references in the CVE record, grouped by the tags the record gives them.
Advisories (1)
- tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-info-disclose-9eJ
Other links (1)
- cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3259
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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