Threats / Cisco / CVE-2023-20269

CVE-2023-20269 · EUVD no mirror located · GCVE no mirror located Verified 2026-09-19

Cisco Adaptive Security Appliance and Firepower Threat Defen vulnerability

Cisco ASA and FTD contain an authentication bypass vulnerability allowing unauthenticated remote attackers to conduct brute force attacks against VPN credentials or establish unauthorized clientless SSL VPN sessions.

Verdict

Today item, not a backlog item.

An unauthenticated remote attacker can exploit weak authentication controls to brute force valid credentials or bypass authentication entirely, gaining unauthorized VPN access to protected networks. Active exploitation and ransomware deployment have been observed.

CISA KEV Yes · 2023-09-13⁵Ransomware use Flagged⁵EPSS 0.25453 (verify live)⁶CVSS 5³CISA SSVC Exploitation: active · Automatable: no · Impact: partial⁴

Is it exploitable?

— the evidence, ranked above the score

Reported exploitation

55 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.

rapid7.com ↗sec.cloudapps.cisco.com ↗bleepingcomputer.com ↗cisa.gov ↗Confirmed

Exploited in the wild

Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-09-13), flagged for known ransomware use.

CISA KEV ↗Confirmed

Probability (EPSS)

EPSS 0.25453 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.

FIRST EPSS ↗High

Severity / affected

CVSS 5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N) · Affected: Cisco, Adaptive Security Appliance and Firepower Threat Defense. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.

CVE.org ↗Reported

Weakness (CWE)

Mapped to CWE-288 Auth Bypass via Alternate Path — weakness family: Authentication.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.

CVE.org ↗Reported

CISA SSVC (triage disposition)

Exploitation: active · Automatable: no · Technical Impact: partialCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.

CISA-ADP ↗Reported

Currency of the record

CISA added this to its KEV catalog 7 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.

CISA KEV ↗CVE.org ↗Reported

WeaknessCWE-288 · Auth Bypass via Alternate PathAuthentication

Who’s exploiting it?

— attribution turns risk into urgency

Akira Ransomware

The #StopRansomware joint advisory AA24-109A reports that Akira ransomware affiliates gain initial access through Cisco VPN appliances lacking MFA, naming the group and the Cisco ASA/FTD CVEs they exploit to do so.¹³

T1133 External Remote Services ↗T1486 Data Encrypted for Impact ↗

Why it matters

— the attack path, told twice: adversary, then board

Front door — unauthenticated access narrative 1

Attacker

I probe the VPN endpoint to identify it as a Cisco ASA or FTD device without requiring authentication.

Business

Perimeter security controls fail to prevent reconnaissance of critical access points.

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker

I conduct brute force attacks against VPN credentials or exploit the authentication bypass to establish a clientless SSL VPN session without valid credentials.

Business

Attackers gain direct network access, bypassing multi-factor authentication and access controls.

Lateral reach — past segmentation narrative 3

Attacker

I establish a persistent presence inside the network to conduct lateral movement and deploy ransomware or exfiltrate sensitive data.

Business

Ransomware campaigns and data breaches compromise business continuity, customer trust, and regulatory compliance.

What to do

— defensible action

Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.¹

Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.

Coverage & confidence

— what we know, and what we don’t

Established (cited)

KEV listing (CISA)

Ransomware-use flag (CISA)

EPSS probability (FIRST)

55 reported-exploitation source(s)

CVSS 5 — CNA-assigned (CVE.org)

CISA SSVC triage disposition (CVE.org ADP)

CWE weakness mapping — CNA-assigned (CVE.org)

Catalogued by cisco (CNA)

Named finder/reporter credit (CVE.org)

Coverage gaps — stated, not hidden

No EUVD / GCVE mirror in feed — single-authority dependency for the identifier.

EPSS & exposure are time-varying; verify live at the source.

Threat-actor attribution not established from feed data — absence of a name is not absence of compromise.

Disclosure & credit²

Catalogued by ciscoCNA

Credited with finding itRapid7finder

Found an error? Propose a correction.

A correction is a cited counter-claim — it must cite a source, gets reviewed by a second human, and is never auto-applied. See the correction convention and our identity npub1j7gt9ky7sfcrjn8jjee6693dkzvk4rahs0fk2suu7968dfns62zs3mqm3y.

With JavaScript off: publish a signed kind 1111 Nostr event tagging ["r", "https://basicsecurity.net/threat/cve-2023-20269.html"], ["v", "sha256:96fbeef42740be94307861c71b6a06a2beb180ba09b2db6647208ee9b7a17bed"] (the record version), plus ["src", "<your source URL>"] and ["t", "correction"], per the correction convention. Our identity: npub1j7gt9ky7sfcrjn8jjee6693dkzvk4rahs0fk2suu7968dfns62zs3mqm3y. Cite-or-die: an event with no src is a coverage finding, not a proposal.