CVE-2020-11683: A timing side channel was discovered in AT91bootstrap before 3.9.2

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MEDIUM 6.8WATCHLISTUPGRADE

CVE-2020-11683 is a medium-severity flaw (CVSS 6.8) affecting at91bootstrap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A timing side channel was discovered in AT91bootstrap before 3.9.2. It can be exploited by attackers with physical access to forge CMAC values and subsequently boot arbitrary code on an affected system.

Why this priority

Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.8 (Medium)
Attack vector	Physical
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-203
Published	2020-09-14
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: linux4sam

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

Am I affected?

Timeline

2020-09-14 14:15 UTCPublished CVE record published
2026-06-17 02:50 UTCUpdated Record last modified

linux4sam at91bootstrap UPGRADE

Affected: >= 3.7.2 and < 3.9.2

Fixed in: 3.9.2

Safe to downgrade to: a release before 3.7.2

1. Check installed version

apt-cache policy at91bootstrap || rpm -q at91bootstrap || at91bootstrap --version

2. UPGRADE to 3.9.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade at91bootstrap

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade at91bootstrap

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 3.7.2 (Debian / Ubuntu)

apt-cache madison at91bootstrap sudo apt install at91bootstrap=<VERSION_BEFORE_3.7.2> sudo apt-mark hold at91bootstrap

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

dnf --showduplicates list at91bootstrap sudo dnf downgrade at91bootstrap-<VERSION_BEFORE_3.7.2> sudo dnf versionlock add at91bootstrap

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-2020-11683?

at91bootstrap: upgrade to 3.9.2. Exact commands for each OS are on this page.

Is CVE-2020-11683 being exploited?

CVE-2020-11683 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-2020-11683 affect?

CVE-2020-11683 affects at91bootstrap. Severity is medium (CVSS 6.8). A timing side channel was discovered in AT91bootstrap before 3.9.2. It can be exploited by attackers with physical access to forge CMAC values and subsequently boot arbitrary code on an affected system.

How urgent is CVE-2020-11683?

Priority 45/100. Public exploit reference; On your watchlist

Related CVEs

CVE-2020-11684 CRITICAL 9.1 UPGRADE AT91bootstrap before 3.9.2 does not properly wipe encryption and authentication keys from memory before passin

References

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