CVE-2020-8299: Citrix ADC and Citrix/NetScaler Gateway 13.0 before 13.0-76.29, 12.1-61.18, 11.1-65.20, Citrix ADC 12.1-FIPS b

Q: How do I fix CVE-2020-8299?

gateway: upgrade to 12.1-61.18, 13.0-76.29; netscaler gateway: upgrade to 11.1-65.20; application delivery controller firmware: upgrade to 11.1-65.20, 12.1-55.238, 12.1-61.18, 13.0-76.29. Exact commands for each OS are on this page.

Q: Is CVE-2020-8299 being exploited?

CVE-2020-8299 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-8299 affect?

CVE-2020-8299 affects gateway, netscaler gateway, application delivery controller firmware. Severity is medium (CVSS 6.5). Citrix ADC and Citrix/NetScaler Gateway 13.0 before 13.0-76.29, 12.1-61.18, 11.1-65.20, Citrix ADC 12.1-FIPS before 12.1-55.238, and Citrix SD-WAN WANOP Edition before 11.4.0, 11.3.2, 11.3.1a, 11.2.3a, 11.1.2c, 10.2.9a suffers from uncontro

Q: How urgent is CVE-2020-8299?

Priority 32/100. No elevated risk signals yet.

Routine

MEDIUM 6.5UPGRADEUPGRADEUPGRADE

CVE-2020-8299 is a medium-severity flaw (CVSS 6.5) affecting gateway, netscaler gateway, application delivery controller firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Citrix ADC and Citrix/NetScaler Gateway 13.0 before 13.0-76.29, 12.1-61.18, 11.1-65.20, Citrix ADC 12.1-FIPS before 12.1-55.238, and Citrix SD-WAN WANOP Edition before 11.4.0, 11.3.2, 11.3.1a, 11.2.3a, 11.1.2c, 10.2.9a suffers from uncontrolled resource consumption by way of a network-based denial-of-service from within the same Layer 2 network segment. Note that the attacker must be in the same Layer 2 network segment as the vulnerable appliance

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-400
Published	2021-06-16
Last modified	2026-06-17

Publisher (CNA): HackerOne · Vendor: citrix

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-06-16 14:15 UTCPublished CVE record published
2026-06-17 03:26 UTCUpdated Record last modified

citrix gateway UPGRADE

Affected: >= 12.1 and < 12.1-61.18 · >= 13.0 and < 13.0-76.29

Fixed in: 12.1-61.18, 13.0-76.29

Safe to downgrade to: a release before 12.1

1. Check installed version

apt-cache policy gateway || rpm -q gateway || gateway --version

2. UPGRADE to 12.1-61.18 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade gateway

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade gateway

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 12.1 (Debian / Ubuntu)

apt-cache madison gateway sudo apt install gateway=<VERSION_BEFORE_12.1> sudo apt-mark hold gateway

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list gateway sudo dnf downgrade gateway-<VERSION_BEFORE_12.1> sudo dnf versionlock add gateway

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.

citrix netscaler gateway UPGRADE

Affected: >= 11.1 and < 11.1-65.20

Fixed in: 11.1-65.20

Safe to downgrade to: a release before 11.1

1. Check installed version

apt-cache policy netscaler-gateway || rpm -q netscaler-gateway || netscaler-gateway --version

2. UPGRADE to 11.1-65.20 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade netscaler-gateway

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade netscaler-gateway

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 11.1 (Debian / Ubuntu)

apt-cache madison netscaler-gateway sudo apt install netscaler-gateway=<VERSION_BEFORE_11.1> sudo apt-mark hold netscaler-gateway

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list netscaler-gateway sudo dnf downgrade netscaler-gateway-<VERSION_BEFORE_11.1> sudo dnf versionlock add netscaler-gateway

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.

citrix application delivery controller firmware UPGRADE

Affected: >= 11.1 and < 11.1-65.20 · >= 12.1 and < 12.1-61.18 · >= 13.0 and < 13.0-76.29 · >= 12.1 and < 12.1-55.238

Fixed in: 11.1-65.20, 12.1-55.238, 12.1-61.18, 13.0-76.29

Safe to downgrade to: a release before 11.1

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.

citrix sd-wan wanop UPGRADE

Affected: >= 10.2 and < 10.2.9a · >= 11.1 and < 11.1.2c · >= 11.2 and < 11.2.3a · >= 11.3 and < 11.3.2

Fixed in: 10.2.9a, 11.1.2c, 11.2.3a, 11.3.2

Safe to downgrade to: a release before 10.2

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.

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-2020-8299?

gateway: upgrade to 12.1-61.18, 13.0-76.29; netscaler gateway: upgrade to 11.1-65.20; application delivery controller firmware: upgrade to 11.1-65.20, 12.1-55.238, 12.1-61.18, 13.0-76.29. Exact commands for each OS are on this page.

Is CVE-2020-8299 being exploited?

CVE-2020-8299 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-2020-8299 affect?

CVE-2020-8299 affects gateway, netscaler gateway, application delivery controller firmware. Severity is medium (CVSS 6.5). Citrix ADC and Citrix/NetScaler Gateway 13.0 before 13.0-76.29, 12.1-61.18, 11.1-65.20, Citrix ADC 12.1-FIPS before 12.1-55.238, and Citrix SD-WAN WANOP Edition before 11.4.0, 11.3.2, 11.3.1a, 11.2.3a, 11.1.2c, 10.2.9a suffers from uncontro

How urgent is CVE-2020-8299?

Priority 32/100. No elevated risk signals yet.

Software pages

Citrix vulnerabilities

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References

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