CASCACascade Atlas

Evidence dossier

CVE-2021-27877

CVE-2021-27877

74.9–95.6Priority evidence range
As known Jul 19, 2026, 5:00 AM UTCgen-56ccdaf9

Normalized restatement

An issue was discovered in Veritas Backup Exec before 21.2. It supports multiple authentication schemes: SHA authentication is one of these. This authentication scheme is no longer used in current versions of the product, but hadn't yet been disabled. An attacker could remotely exploit this scheme to gain unauthorized access to an Agent and execute privileged commands.

State
PUBLISHED
Published
Mar 1, 2021
Updated
Oct 21, 2025
Evidence coverage
72%
CISA KEVCatalog member

Apply updates per vendor instructions.

FIRST EPSS64.91%

2026-07-18 · v2026.06.15 · percentile 99.2%

Source stateConflict visible

Distinct CVSS assessments remain side by side; none are averaged.

Source comparison

Who said what

CISA-ADPindependent enrichment
container

CISA ADP Vulnrichment

CVEderivative copy
container

CVE Program Container

mitreoriginal assertion
container

An issue was discovered in Veritas Backup Exec before 21.2. It supports multiple authentication schemes: SHA authentication is one of these. This authentication scheme is no longer used in current versions of the product, but hadn't yet been disabled. An attacker could remotely exploit this scheme to gain unauthorized access to an Agent and execute privileged commands.

CISA KEVoriginal assertion
observed_exploitation

Veritas Backup Exec Agent Improper Authentication Vulnerability

FIRST EPSSoriginal assertion
model_probability

Probability 0.649100000000; percentile 0.991610000000

Applicability

Cited product scope

Trace impact →
n/an/a
[{"status": "affected", "version": "n/a"}]unknown
Unknown vendorUnknown product
cpe:2.3:a:veritas:backup_exec:*:*:*:*:*:*:*:*; end excluding 21.2supported

Assessments

CVSS by origin

9.8
nvd@nist.govCVSS 3.1 · role PrimaryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5
nvd@nist.govCVSS 2.0 · role PrimaryAV:N/AC:L/Au:N/C:P/I:P/A:P
8.2
cve@mitre.orgCVSS 3.1 · role SecondaryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
8.2
mitreCVSS 3.1 · role unknownCVSS:3.1/AC:L/AV:N/A:N/C:H/I:L/PR:N/S:U/UI:N

Limitations and unknowns

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; unresolved scope remains unknown.
  • NVD-carried upstream facts remain derivative and are not independent corroboration.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Factor D is unknown in Public Core because no accepted canonical mapping-obligation ledger is present.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.