Cisco ASA and FTD Information Disclosure Vulnerability

Known exploitedExploited · KEV 2024-02-15RansomwareCVE-2020-3259CWE-200

Exploited since 2024-02-15. No WAF vendor names it yet.

Edge rules

0/8

Our test

No exploit yet

CVSS

7.5

EPSS

71.5% Top 0.6%

Posts, 14d

Published

2020-05-06

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.

Known exploitedLast checked 2026-11-04

The risk

CISA lists CVE-2020-3259 as exploited in the wild since 2024-02-15, including known use in ransomware campaigns. It is reachable over the network without credentials or any user interaction (CVSS 7.5). No edge WAF vendor names it in a changelog, so default managed rules may or may not catch it.

Who is affected

Teams running Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). Affected versions are in the vendor advisory. Prioritise internet-facing instances.

Next steps

Find the version you run. On the device CLI:
```
show version
```
Apply the vendor's fix; the advisory lists the affected and fixed versions. 20200506 Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Information Disclosure Vulnerability ↗
CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. US federal agencies must act by 2024-03-07.
Review exposed instances for signs of compromise: it was exploited before many systems were patched, and a later patch does not undo access already gained.
Do not rely on WAF defaults: no edge vendor names this CVE. Restrict access to the vulnerable component or add a custom rule until it is patched. Edge coverage
Check which WAF sits in front of your site and whether it covers this CVE. Check your domain

Exploitation activity

Last 90 days

Honeypot days: 0 / 90
Last attempt seen: —
Listed exploited: —
Telegram claims: 1 days, unverified

Honeypot hits

Telegram claims

Edge coverage

Claimed by vendors

CloudflareBefore feed historyOlder than its feed AWSNo public claimNot named Microsoft AzureNo public claimNot named Google CloudBefore feed historyOlder than its feed FastlyBefore feed historyOlder than its feed F5Before feed historyOlder than its feed AkamaiNo public sourceNo public changelog OWASP CRSBefore feed historyOlder than its feed

Attack traffic on Cloudflare

Cloudflare Radar

Broken Authentication14% of mitigated layer 7 attacks, 7 days
Rules for named CVEs5.9% of mitigated layer 7 attacks, 7 days

Radar groups Cloudflare's WAF managed rules by category; it does not publish counts per CVE. These shares show how much attack traffic targets this kind of flaw across Cloudflare's network (28-day trend). They are not compromised systems, and seeing few attempts on Cloudflare does not prove an absence elsewhere. Radar data as of 2026-11-03. Radar ↗

Check your exposure with an agent

Read-only

Copy this into an agent with access to your infrastructure. It asks for an evidence-based, read-only assessment: affected systems, exposure, compensating controls and what is still unknown. It does not scan or change anything by itself.

Prompt12 lines

Assess whether the infrastructure available to you is affected by CVE-2020-3259 (Cisco ASA and FTD Information Disclosure Vulnerability). Perform a read-only assessment within your authorized access. Do not send exploit traffic, scan third-party systems, change configuration or restart services.

1. Verify the CVE record at https://www.cve.org/CVERecord?id=CVE-2020-3259 and the vendor advisories (https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-info-disclose-9eJtycMB). Establish affected and fixed versions, including vendor backports. Cite sources and retrieval dates; flag anything you cannot verify.
2. Inventory deployments of Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD): asset, environment, owner where known, installed version or build, and how you confirmed it (package metadata, a version endpoint, image tags), e.g. `show version` (on the device CLI). An image tag alone does not prove the running version.
3. Identify which deployments are reachable from the internet or untrusted networks, and through which paths (direct origin, load balancer, CDN or WAF).
4. Assess compensating controls separately from patch status. Current edge WAF coverage for this CVE: no edge WAF vendor names it. Live data: https://cve.vigilbase.com/api/v1/cves/CVE-2020-3259. Check whether the rule is enabled and in block mode on each path, and whether any path bypasses the WAF. A WAF rule is not a patch.
5. It is known exploited (CISA KEV): review logs on exposed instances for signs of exploitation before and after patching.

Return a short summary and a table: asset | version/build | assessment (affected, fixed, not applicable, unknown) | exposure | compensating control | evidence | next action. List what you could not assess and the access needed to resolve it. Do not infer absence of compromise from patch status or a lack of alerts.

Remediation guidance: Apply the vendor's fix; the advisory lists the affected and fixed versions. CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. US federal agencies must act by 2024-03-07.
More: https://cve.vigilbase.com/cve/CVE-2020-3259

Sources

Cited

CVE record

CVSS 3.0 7.5 (high). Weakness: CWE-200.

CVE-2020-3259 ↗NVD ↗

Vendor advisory

Fixes and mitigations the CVE record links to. Check affected builds against the vendor, including backports.

20200506 Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Information Disclosure Vulnerability ↗

Exploit evidence

No public exploit code found in Exploit-DB, Metasploit, nuclei-templates or GitHub. That does not mean none exists.

Seen exploited

Claimed in 1 Telegram post (unverified).

CISA KEV

Added 2024-02-15, federal due date 2024-03-07, known ransomware use (catalog 2026.11.03, checked 2026-11-04).

CISA KEV catalog ↗

EPSS

71.5% probability of exploitation activity in the next 30 days, higher than 99% of CVEs (2026-11-02).

FIRST EPSS ↗

WAF vendor statements

No edge vendor changelog names it.

Ask Vigil

AI · answers from this page

Ask about CVE-2020-3259: who's covered, what to patch first, how vendors compare. I cite sources and won't help with attacks.

Severity, decoded

CVSS 3.0

7.5High

High · 7.5 / 10

Exploitable over the network, with no privileges and no user interaction, leading to full loss of confidentiality.

Over the internetNo login neededNo user actionWorks reliablySerious impact

How the score is built8 metrics

Attack vectorAn attacker can reach it over the internet; no access to your network needed.
Network
Attack complexityNo special conditions are needed; the attack works reliably.
Low
Privileges requiredNo account or login is needed.
None
User interactionNo one has to click or open anything; the attack works on its own.
None
ScopeThe damage stays within the vulnerable component.
Unchanged
Confidentiality impactAn attacker can read all data the affected component holds, or the most sensitive parts of it.
High
Integrity impactData cannot be changed by the attacker.
None
Availability impactThe component keeps working normally.
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CISA's assessmentSSVC, from the CVE record

ExploitationActive

Attackers are exploiting this in the wild.

AutomatableYes

Attackers can script the attack end to end and hit many targets at once.

Technical impactPartial

A successful attack gives limited control over the affected software or limited access to its data.

Public exploits

None found

0 Metasploit0 Exploit-DB0 Scanner template0 GitHub PoCs

No exploit in Exploit-DB or Metasploit, and no scanner template. That lowers, but doesn't remove, the chance of mass exploitation.

Timeline

2020-05-06
CVE published
CVE List
2024-02-15
Added to CISA KEV
Confirmed exploitation in the wild