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CVE-2025-20363: A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco

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CRITICAL 9.0REMOTEMITIGATEUPGRADEMITIGATE

CVE-2025-20363 is a critical-severity flaw (CVSS 9.0) affecting ios xr, adaptive security appliance software, ios. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software, Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, remote attacker (Cisco ASA and FTD Software) or authenticated, remote attacker (Cisco IOS, IOS XE, and IOS XR Software) with low user privileges to execute arbitrary code on an affected devic

Why this priority

  • Critical severity
  • EPSS top 6%: very likely to be exploited
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score9.0 (Critical)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededNone
User interactionNone
EPSS exploit chance6.9% (top 6%)
CISA exploited listNo
WeaknessCWE-122
Published2025-09-25
Last modified2026-10-18
Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco

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Last updated 2026-10-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

cisco ios xr MITIGATE
Affected: 6.5.1 · 6.5.2 · 6.5.3 · 6.6.2 · 6.6.3 · 6.6.25 · 6.7.1 · 6.7.2
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.5.1
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
cisco adaptive security appliance software UPGRADE
Affected: >= 9.12 and < 9.12.4.72 · >= 9.14 and < 9.14.4.28 · >= 9.16 and < 9.16.4.84 · >= 9.17.1 and < 9.18.4.57 · >= 9.19.1 and < 9.19.1.42 · >= 9.20.1 and < 9.20.3.16 · >= 9.22 and < 9.22.2 · >= 9.23 and < 9.23.1.3
Fixed in: 9.12.4.72, 9.14.4.28, 9.16.4.84, 9.18.4.57, 9.19.1.42, 9.20.3.16, 9.22.2, 9.23.1.3
Safe to downgrade to: a release before 9.12
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
cisco ios MITIGATE
Affected: >= 12.2\(15\)b and <= 15.9\(3\)m11
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
cisco ios xe UPGRADE
Affected: >= 3.2.0sg and <= 17.17.1
Fixed in: newer than 17.17.1
Safe to downgrade to: a release before 3.2.0sg
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
cisco secure firewall threat defense UPGRADE
Affected: >= 7.0.0 and < 7.0.8 · >= 7.1.0 and < 7.2.10 · >= 7.3.0 and < 7.4.2.3 · >= 7.7.0 and < 7.7.10 · 7.6.0
Fixed in: 7.0.8, 7.2.10, 7.4.2.3, 7.7.10
Safe to downgrade to: a release before 7.0.0
1. Check installed version
apt-cache policy secure-firewall-threat-defense || rpm -q secure-firewall-threat-defense || secure-firewall-threat-defense --version
2. UPGRADE to 7.0.8 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade secure-firewall-threat-defense
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade secure-firewall-threat-defense
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 7.0.0 (Debian / Ubuntu)
apt-cache madison secure-firewall-threat-defense sudo apt install secure-firewall-threat-defense=<VERSION_BEFORE_7.0.0> sudo apt-mark hold secure-firewall-threat-defense
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list secure-firewall-threat-defense sudo dnf downgrade secure-firewall-threat-defense-<VERSION_BEFORE_7.0.0> sudo dnf versionlock add secure-firewall-threat-defense
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.
Fedora 46 · wordpress · FIXED · 7.1.4-1.fc46 · FEDORA-2026-907394725e · source
sudo dnf upgrade --advisory=FEDORA-2026-907394725e
Fedora ELN · rhc · FIXED · 0.3.15-1.eln159 · FEDORA-2026-1cd9f35750 · source
sudo dnf upgrade --advisory=FEDORA-2026-1cd9f35750
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-20363?

ios xr: mitigate or apply the listed mitigation; adaptive security appliance software: upgrade to 9.12.4.72, 9.14.4.28, 9.16.4.84, 9.18.4.57, 9.19.1.42, 9.20.3.16, 9.22.2, 9.23.1.3; ios: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-20363 being exploited?

CVE-2025-20363 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-20363 affect?

CVE-2025-20363 affects ios xr, adaptive security appliance software, ios. Severity is critical (CVSS 9.0). A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software, Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow a

How urgent is CVE-2025-20363?

Priority 60/100. Critical severity; EPSS top 6%: very likely to be exploited; Remotely exploitable, no login, no user action

Software pages

iOS vulnerabilities · Cisco IOS XE vulnerabilities · Cisco ASA vulnerabilities · Cisco vulnerabilities

Related CVEs

References

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