Cyber Resilience

CVE-2021-27878

Veritas Backup Exec ≤ 21.2

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linked
Published
01 March 2021
Modified
03 November 2025
KEV Added
07 April 2023
Patch / advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.24 98th percentile
Risk Priority 90 floored blend · peak EPSS

Summary

CVE-2021-27878 is a high-severity an unspecified weakness vulnerability in Veritas Backup Exec. Its CVSS base score is 8.8 (High).

Operationally, ranked in the top 2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2021-27878 affects Veritas Backup Exec versions prior to 21.2. The flaw resides in the SHA Authentication scheme used for client-to-Agent communication. Although the protocol is intended to run over TLS, the authentication mechanism can be bypassed, allowing an unauthenticated network attacker to complete the handshake and establish an authenticated session.

Once the session is established, the attacker can issue arbitrary data management protocol commands. These commands execute with system-level privileges on the target host, resulting in full remote code execution. The vulnerability carries a CVSS 3.1 score of 8.8, reflecting network attack vector, low complexity, and high impact on confidentiality, integrity, and availability.

Veritas security advisory VTS21-001 addresses the issue and recommends upgrading to Backup Exec 21.2 or later. The flaw appears in the CISA Known Exploited Vulnerabilities catalog, and public exploit code has been published on PacketStorm, confirming active interest from attackers.

EU & UK References

Vulnerability Data

An issue was discovered in Veritas Backup Exec before 21.2. The communication between a client and an Agent requires successful authentication, which is typically completed over a secure TLS communication. However, due to a vulnerability in the SHA Authentication scheme,…

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an attacker is able to gain unauthorized access and complete the authentication process. Subsequently, the client can execute data management protocol commands on the authenticated connection. The attacker could use one of these commands to execute an arbitrary command on the system using system privileges.

CWE(s)
KEV Date Added
07 April 2023

Related Threats

CVEs Like This One

CVE-2021-27876Same product: Veritas Backup Execboth on KEV
CVE-2021-27877Same product: Veritas Backup Execboth on KEV
CVE-2024-33671Same product: Veritas Backup Exec
CVE-2017-8895Same product: Veritas Backup Exec
CVE-2024-33673Same product: Veritas Backup Exec
CVE-2023-26789Same vendor: Veritas
CVE-2023-38404Same vendor: Veritas
CVE-2024-52943Same vendor: Veritas
CVE-2023-28759Same vendor: Veritas
CVE-2024-52944Same vendor: Veritas

Affected Assets

veritas
backup exec
≤ 21.2

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References