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CVE-2021-4048: An out-of-bounds read flaw was found in the CLARRV, DLARRV, SLARRV, and ZLARRV functions in lapack through ver

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CRITICAL 9.1REMOTEWATCHLISTUPGRADEUPGRADEUPGRADE

CVE-2021-4048 is a critical-severity flaw (CVSS 9.1) affecting lapack, openblas, julia. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An out-of-bounds read flaw was found in the CLARRV, DLARRV, SLARRV, and ZLARRV functions in lapack through version 3.10.0, as also used in OpenBLAS before version 0.3.18. Specially crafted inputs passed to these functions could cause an application using lapack to crash or possibly disclose portions of its memory.

Why this priority

  • Critical severity
  • Remotely exploitable, no login, no user action
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score9.1 (Critical)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance2.8% (top 14%)
CISA exploited listNo
WeaknessCWE-125
Published2021-12-08
Last modified2026-06-17
Publisher (CNA): Red Hat, Inc. · Vendor: julialang · lapack project · openblas project · redhat

Share: LinkedIn · X · Reddit

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

Am I affected?

Timeline

lapack project lapack UPGRADE
Affected: <= 3.10.0
Fixed in: newer than 3.10.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy lapack || rpm -q lapack || lapack --version
2. UPGRADE to newer than 3.10.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade lapack
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade lapack
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
openblas project openblas UPGRADE
Affected: < 0.3.18
Fixed in: 0.3.18
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy openblas || rpm -q openblas || openblas --version
2. UPGRADE to 0.3.18 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade openblas
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade openblas
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
julialang julia UPGRADE
Affected: <= 1.6.3 · 1.7.0 beta1 · 1.7.0 beta2 · 1.7.0 beta3 · 1.7.0 beta4 · 1.7.0 rc1
Fixed in: newer than 1.6.3
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy julia || rpm -q julia || julia --version
2. UPGRADE to newer than 1.6.3 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade julia
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade julia
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
redhat ceph storage DOWNGRADE
Affected: 2.0 · 3.0 · 4.0 · 5.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.0
1. Check installed version
apt-cache policy ceph-storage || rpm -q ceph-storage || ceph-storage --version
2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)
apt-cache madison ceph-storage sudo apt install ceph-storage=<VERSION_BEFORE_2.0> sudo apt-mark hold ceph-storage
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list ceph-storage sudo dnf downgrade ceph-storage-<VERSION_BEFORE_2.0> sudo dnf versionlock add ceph-storage
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.
redhat openshift container storage DOWNGRADE
Affected: 4.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 4.0
1. Check installed version
apt-cache policy openshift-container-storage || rpm -q openshift-container-storage || openshift-container-storage --version
2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)
apt-cache madison openshift-container-storage sudo apt install openshift-container-storage=<VERSION_BEFORE_4.0> sudo apt-mark hold openshift-container-storage
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list openshift-container-storage sudo dnf downgrade openshift-container-storage-<VERSION_BEFORE_4.0> sudo dnf versionlock add openshift-container-storage
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.
redhat openshift data foundation DOWNGRADE
Affected: 4.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 4.0
1. Check installed version
apt-cache policy openshift-data-foundation || rpm -q openshift-data-foundation || openshift-data-foundation --version
2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)
apt-cache madison openshift-data-foundation sudo apt install openshift-data-foundation=<VERSION_BEFORE_4.0> sudo apt-mark hold openshift-data-foundation
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list openshift-data-foundation sudo dnf downgrade openshift-data-foundation-<VERSION_BEFORE_4.0> sudo dnf versionlock add openshift-data-foundation
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-2021-4048?

lapack: upgrade to newer than 3.10.0; openblas: upgrade to 0.3.18; julia: upgrade to newer than 1.6.3. Exact commands for each OS are on this page.

Is CVE-2021-4048 being exploited?

CVE-2021-4048 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-2021-4048 affect?

CVE-2021-4048 affects lapack, openblas, julia. Severity is critical (CVSS 9.1). An out-of-bounds read flaw was found in the CLARRV, DLARRV, SLARRV, and ZLARRV functions in lapack through version 3.10.0, as also used in OpenBLAS before version 0.3.18. Specially crafted inputs passed to these functions could cause an app

How urgent is CVE-2021-4048?

Priority 63/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Red Hat OpenShift vulnerabilities · Ceph vulnerabilities

References

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