Threats / Veritas / CVE-2021-27878
CVE-2021-27878
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Veritas Backup Exec Agent vulnerability
Veritas Backup Exec Agent contains an authentication bypass vulnerability allowing remote command execution via data management protocol commands, exploited in ransomware campaigns.
Verdict
Today item, not a backlog item.
An unauthenticated attacker can execute arbitrary commands on affected Backup Exec Agent systems through a protocol-level authentication weakness, enabling full system compromise and data exfiltration in active ransomware operations.
CISA KEV Yes · 2023-04-075Ransomware use Flagged5EPSS 0.23952 (verify live)6CVSS 8.83CISA SSVC Exploitation: active · Automatable: no · Impact: total4Exploit Weaponized · public exploit · Metasploit module13
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
10 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-04-07), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.23952 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 8.8 (CVSS:3.1/AC:L/AV:N/A:H/C:H/I:H/PR:L/S:U/UI:N) · Affected: Veritas, Backup Exec Agent. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-287 Improper Authentication — weakness family: Authentication.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 767 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a functional/weaponized public exploit). Catalog entries: Metasploit module. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious data management protocol command targeting the Backup Exec Agent service.
Business
The organization's backup infrastructure becomes an attack vector rather than a recovery asset.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I bypass authentication controls and execute arbitrary commands with the privileges of the Agent process.
Business
Attackers gain persistent access to systems managing critical backup data and recovery operations.
3
Lateral reach — past segmentation narrative 3
Attacker
I deploy ransomware payloads across the backup environment to encrypt or destroy recovery capabilities.
Business
The organization loses ability to recover from attacks, facing extended downtime and potential total data loss.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05