CVE-2021-42739: The firewire subsystem in the Linux kernel through 5.14.13 has a buffer overflow related to drivers/media/fire

Routine

MEDIUM 6.7WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2021-42739 is a medium-severity flaw (CVSS 6.7) affecting linux kernel, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The firewire subsystem in the Linux kernel through 5.14.13 has a buffer overflow related to drivers/media/firewire/firedtv-avc.c and drivers/media/firewire/firedtv-ci.c, because avc_ca_pmt mishandles bounds checking.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.7 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-10-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · fedoraproject · linux · oracle · starwindsoftware

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

Am I affected?

Timeline

2021-10-20 07:15 UTCPublished CVE record published
2026-06-17 04:10 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: <= 5.14.13

Fixed in: newer than 5.14.13

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.

fedoraproject fedora MITIGATE

Affected: 33 · 34 · 35

Fixed in: no fixed release known

Safe to downgrade to: a release before 33

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.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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.

starwindsoftware starwind san \& nas DOWNGRADE

Affected: v8r12

Fixed in: no fixed release known

Safe to downgrade to: a release before v8r12

1. Check installed version

apt-cache policy starwind-san--nas || rpm -q starwind-san--nas || starwind-san--nas --version

2. No fixed release: DOWNGRADE to a release before v8r12 (Debian / Ubuntu)

apt-cache madison starwind-san--nas sudo apt install starwind-san--nas=<VERSION_BEFORE_v8r12> sudo apt-mark hold starwind-san--nas

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list starwind-san--nas sudo dnf downgrade starwind-san--nas-<VERSION_BEFORE_v8r12> sudo dnf versionlock add starwind-san--nas

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.

starwindsoftware starwind virtual san DOWNGRADE

Affected: v8r13 14338

Fixed in: no fixed release known

Safe to downgrade to: a release before v8r13

1. Check installed version

apt-cache policy starwind-virtual-san || rpm -q starwind-virtual-san || starwind-virtual-san --version

2. No fixed release: DOWNGRADE to a release before v8r13 (Debian / Ubuntu)

apt-cache madison starwind-virtual-san sudo apt install starwind-virtual-san=<VERSION_BEFORE_v8r13> sudo apt-mark hold starwind-virtual-san

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list starwind-virtual-san sudo dnf downgrade starwind-virtual-san-<VERSION_BEFORE_v8r13> sudo dnf versionlock add starwind-virtual-san

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.

oracle communications cloud native core binding support function DOWNGRADE

Affected: 22.1.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 22.1.3

1. Check installed version

apt-cache policy communications-cloud-native-core-binding-support-function || rpm -q communications-cloud-native-core-binding-support-function || communications-cloud-native-core-binding-support-function --version

2. No fixed release: DOWNGRADE to a release before 22.1.3 (Debian / Ubuntu)

apt-cache madison communications-cloud-native-core-binding-support-function sudo apt install communications-cloud-native-core-binding-support-function=<VERSION_BEFORE_22.1.3> sudo apt-mark hold communications-cloud-native-core-binding-support-function

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list communications-cloud-native-core-binding-support-function sudo dnf downgrade communications-cloud-native-core-binding-support-function-<VERSION_BEFORE_22.1.3> sudo dnf versionlock add communications-cloud-native-core-binding-support-function

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.

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-2021-42739?

linux kernel: upgrade to newer than 5.14.13; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-42739 being exploited?

CVE-2021-42739 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-2021-42739 affect?

CVE-2021-42739 affects linux kernel, fedora, debian linux. Severity is medium (CVSS 6.7). The firewire subsystem in the Linux kernel through 5.14.13 has a buffer overflow related to drivers/media/firewire/firedtv-avc.c and drivers/media/firewire/firedtv-ci.c, because avc_ca_pmt mishandles bounds checking.

How urgent is CVE-2021-42739?

Priority 39/100. On your watchlist

Software pages

Linux kernel vulnerabilities · Debian vulnerabilities

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References

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