# CASCA evidence receipt — CVE-2021-27876

- Generation: `gen-56ccdaf914f7b4be95b689ccae7dc20d`
- As known: 2026-07-19T05:00:42+00:00
- Comparison: first_public_core_generation
- Score policy: public-priority-v1.0.1
- Conflict: not observed in this generation

## Source assertions

- **CISA-ADP** (independent_enrichment): container — CISA ADP Vulnrichment
  - Observed: 2026-07-19T04:27:06.398189+00:00
  - Citation: https://www.cve.org/CVERecord?id=CVE-2021-27876
- **CVE** (derivative_copy): container — CVE Program Container
  - Observed: 2026-07-19T04:27:06.398189+00:00
  - Citation: https://www.cve.org/CVERecord?id=CVE-2021-27876
- **mitre** (original_assertion): container — 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, 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. By using crafted input parameters in one of these commands, an attacker can access an arbitrary file on the system using System privileges.
  - Observed: 2026-07-19T04:27:06.398189+00:00
  - Citation: https://www.cve.org/CVERecord?id=CVE-2021-27876
- **CISA KEV** (original_assertion): observed_exploitation — Veritas Backup Exec Agent File Access Vulnerability
  - Observed: 2026-07-19T04:54:04.25158+00:00
  - Citation: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- **FIRST EPSS** (original_assertion): model_probability — Probability 0.134110000000; percentile 0.959990000000
  - Observed: 2026-07-19T04:54:35.756809+00:00
  - Citation: https://www.first.org/epss/data_stats.html

## CVSS assessments

- **nvd@nist.gov** (Primary, CVSS 3.1): 8.1 — score eligible
  - Evidence class: nvd_enrichment_exact; source rank: 0
  - Validation: valid_match
  - Vector: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`
- **nvd@nist.gov** (Primary, CVSS 2.0): 7.5 — score eligible
  - Evidence class: nvd_enrichment_exact; source rank: 0
  - Validation: valid_match
  - Vector: `AV:N/AC:L/Au:S/C:C/I:P/A:N`
- **cve@mitre.org** (Secondary, CVSS 3.1): 8.1 — score eligible
  - Evidence class: exact_record_cna; source rank: 1
  - Validation: valid_match
  - Vector: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`
- **mitre** (unknown, CVSS 3.1): 8.1 — display only
  - Evidence class: direct_cve_record_display_only; source rank: not applicable
  - Validation: display-only direct record assessment
  - Vector: `CVSS:3.1/AC:L/AV:N/A:N/C:H/I:H/PR:L/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.

Generated from CASCA normalized evidence. This receipt is not proof that an asset is affected, unaffected, safe, or fixed.