CVE-2020-8503: Biscom Secure File Transfer (SFT) 5.0.1050 through 5.1.1067 and 6.0.1000 through 6.0.1003 allows Insecure Dire

Routine

MEDIUM 6.5UPGRADE

CVE-2020-8503 is a medium-severity flaw (CVSS 6.5) affecting secure file transfer. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Biscom Secure File Transfer (SFT) 5.0.1050 through 5.1.1067 and 6.0.1000 through 6.0.1003 allows Insecure Direct Object Reference (IDOR) by an authenticated sender because of an error in a file-upload feature. This is fixed in 5.1.1068 and 6.0.1004.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-639
Published	2020-01-31
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: biscom

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

Am I affected?

Timeline

2020-01-31 20:15 UTCPublished CVE record published
2026-06-17 03:26 UTCUpdated Record last modified

biscom secure file transfer UPGRADE

Affected: >= 5.0.1050 and <= 5.1.1067 · >= 6.0.1000 and <= 6.0.1003

Fixed in: newer than 6.0.1003

Safe to downgrade to: a release before 5.0.1050

1. Check installed version

apt-cache policy secure-file-transfer || rpm -q secure-file-transfer || secure-file-transfer --version

2. UPGRADE to newer than 6.0.1003 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade secure-file-transfer

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade secure-file-transfer

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 5.0.1050 (Debian / Ubuntu)

apt-cache madison secure-file-transfer sudo apt install secure-file-transfer=<VERSION_BEFORE_5.0.1050> sudo apt-mark hold secure-file-transfer

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

dnf --showduplicates list secure-file-transfer sudo dnf downgrade secure-file-transfer-<VERSION_BEFORE_5.0.1050> sudo dnf versionlock add secure-file-transfer

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-2020-8503?

secure file transfer: upgrade to newer than 6.0.1003. Exact commands for each OS are on this page.

Is CVE-2020-8503 being exploited?

CVE-2020-8503 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-2020-8503 affect?

CVE-2020-8503 affects secure file transfer. Severity is medium (CVSS 6.5). Biscom Secure File Transfer (SFT) 5.0.1050 through 5.1.1067 and 6.0.1000 through 6.0.1003 allows Insecure Direct Object Reference (IDOR) by an authenticated sender because of an error in a file-upload feature. This is fixed in 5.1.1068 and

How urgent is CVE-2020-8503?

Priority 36/100. No elevated risk signals yet.

Related CVEs

CVE-2020-8796 CRITICAL 9.8 UPGRADE Biscom Secure File Transfer (SFT) before 5.1.1071 and 6.0.1xxx before 6.0.1005 allows Remote Code Execution on
CVE-2020-27646 MEDIUM 6.5 UPGRADE Biscom Secure File Transfer (SFT) before 5.1.1082 and 6.x before 6.0.1011 allows user credential theft.
CVE-2017-5247 MEDIUM 5.4 MITIGATE Biscom Secure File Transfer is vulnerable to cross-site scripting in the File Name field
CVE-2017-5246 MEDIUM 4.3 MITIGATE Biscom Secure File Transfer is vulnerable to AngularJS expression injection in the Display Name field
CVE-2017-5241 MEDIUM 5.4 UPGRADE Biscom Secure File Transfer versions 5.0.0.0 trough 5.1.1024 are vulnerable to post-authentication persistent

References

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