CVE-2021-39271: OrbiTeam BSCW Classic before 7.4.3 allows authenticated remote code execution (RCE) during archive extraction

This month

HIGH 8.8UPGRADE

CVE-2021-39271 is a high-severity flaw (CVSS 8.8) affecting bscw classic. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OrbiTeam BSCW Classic before 7.4.3 allows authenticated remote code execution (RCE) during archive extraction via attacker-supplied Python code in the class attribute of a .bscw file. This is fixed in 5.0.12, 5.1.10, 5.2.4, 7.3.3, and 7.4.3.

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	3.7% (top 10%)
CISA exploited list	No
Published	2021-08-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: bscw

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

Am I affected?

Timeline

2021-08-30 05:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

bscw bscw classic UPGRADE

Affected: < 5.0.12 · >= 5.1.0 and < 5.1.10 · >= 5.2.0 and < 5.2.4 · >= 7.3.0 and < 7.3.3 · >= 7.4.0 and < 7.4.3

Fixed in: 5.0.12, 5.1.10, 5.2.4, 7.3.3, 7.4.3

Safe to downgrade to: a release before 5.1.0

1. Check installed version

apt-cache policy bscw-classic || rpm -q bscw-classic || bscw-classic --version

2. UPGRADE to 5.0.12 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade bscw-classic

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade bscw-classic

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 5.1.0 (Debian / Ubuntu)

apt-cache madison bscw-classic sudo apt install bscw-classic=<VERSION_BEFORE_5.1.0> sudo apt-mark hold bscw-classic

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

dnf --showduplicates list bscw-classic sudo dnf downgrade bscw-classic-<VERSION_BEFORE_5.1.0> sudo dnf versionlock add bscw-classic

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-2021-39271?

bscw classic: upgrade to 5.0.12, 5.1.10, 5.2.4, 7.3.3, 7.4.3. Exact commands for each OS are on this page.

Is CVE-2021-39271 being exploited?

CVE-2021-39271 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-2021-39271 affect?

CVE-2021-39271 affects bscw classic. Severity is high (CVSS 8.8). OrbiTeam BSCW Classic before 7.4.3 allows authenticated remote code execution (RCE) during archive extraction via attacker-supplied Python code in the class attribute of a .bscw file. This is fixed in 5.0.12, 5.1.10, 5.2.4, 7.3.3, and 7.4.3

How urgent is CVE-2021-39271?

Priority 58/100. High severity; Public exploit reference

Software pages

Python vulnerabilities

Related CVEs

CVE-2021-36359 HIGH 8.8 UPGRADE OrbiTeam BSCW Classic before 7.4.3 allows exportpdf authenticated remote code execution (RCE) via XML tag inje

References

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