How severe is CVE-2020-4042?

CVE-2020-4042 has a CVSS 3.x base score of 6.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2020-4042 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-4042?

CVE-2020-4042 primarily affects Bareos. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-4042?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-4042 published?

CVE-2020-4042 was published on 2020-07-10 and last updated on 2026-06-17.

CVE-2020-4042

CVE-2020-4042 is a medium-severity vulnerability in Bareos with a CVSS 3.x base score of 6.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-294.

Key facts

Severity: Medium (CVSS 3.x base score 6.8)
CVSS v2: 4.3
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-294
Affected product: Bareos
Published: 2020-07-10
Last modified: 2026-06-17

Description

Bareos before version 19.2.8 and earlier allows a malicious client to communicate with the director without knowledge of the shared secret if the director allows client initiated connection and connects to the client itself. The malicious client can replay the Bareos director's cram-md5 challenge to the director itself leading to the director responding to the replayed challenge. The response obtained is then a valid reply to the directors original challenge. This is fixed in version 19.2.8.

Frequently asked questions

What is CVE-2020-4042?: Bareos before version 19.2.8 and earlier allows a malicious client to communicate with the director without knowledge of the shared secret if the director allows client initiated connection and connects to the client itself. The malicious client can replay the Bareos director's cram-md5 challenge to the director itself leading to the director responding to the replayed challenge. The response obtained is then a valid reply to the directors original challenge. This is fixed in version 19.2.8.
How severe is CVE-2020-4042?: CVE-2020-4042 has a CVSS 3.x base score of 6.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2020-4042 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-4042?: CVE-2020-4042 primarily affects Bareos. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-4042?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-4042 published?: CVE-2020-4042 was published on 2020-07-10 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:bareos:bareos:*:*:*:*:*:*:*:*
cpe:2.3:a:bareos:bareos:19.2.8:pre:*:*:*:*:*:*

More vulnerabilities in Bareos

CVE-2022-24755 — High (CVSS 8.1): Bareos is open source software for backup, archiving, and recovery of data for operating systems. When Bareos Director…
CVE-2017-14610 — High (CVSS 7.8): bareos-dir, bareos-fd, and bareos-sd in bareos-core in Bareos 16.2.6 and earlier create a PID file after dropping…
CVE-2022-24756 — High (CVSS 7.5): Bareos is open source software for backup, archiving, and recovery of data for operating systems. When Bareos Director…
CVE-2020-11061 — Medium (CVSS 6.0): In Bareos Director less than or equal to 16.2.10, 17.2.9, 18.2.8, and 19.2.7, a heap overflow allows a malicious client…

All CVEs affecting Bareos →

Other CWE-294 (Authentication Bypass by Capture-replay) vulnerabilities

CVE-2025-49752 — Critical (CVSS 10.0): Azure Bastion Elevation of Privilege Vulnerability
CVE-2026-11856 — Critical (CVSS 9.8): Successfully using libcurl to do a transfer to a specific HTTP origin (`hostA`) with **Digest** authentication and then…
CVE-2026-32987 — Critical (CVSS 9.8): OpenClaw before 2026.3.13 allows bootstrap setup codes to be replayed during device pairing verification in…
CVE-2025-67135 — Critical (CVSS 9.8): Weak Security in the PF-50 1.2 keyfob of PGST PG107 Alarm System 1.25.05.hf allows attackers to compromise access…
CVE-2025-65552 — Critical (CVSS 9.8): D3D Wi-Fi Home Security System ZX-G12 v2.1.1 is vulnerable to RF replay attacks on the 433 MHz sensor communication…
CVE-2024-38438 — Critical (CVSS 9.8): D-Link - CWE-294: Authentication Bypass by Capture-replay

Browse all CWE-294 (Authentication Bypass by Capture-replay) vulnerabilities →