CVE-2021-27876

HIGHNVD 8.19.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2023-04-07), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 8.1 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 4 sources updated this weekExploited in the wild
8.1
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 13%CVSS: 8.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
8.1
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS
96.0%
KEV
⚠ Exploited

Published

March 1, 2021

Last Modified

November 3, 2025

Advisory Details (2)

Auto-updated Jun 3, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27876
generic

Packet Storm

http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 48× in last 7d / 229× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 447 total refreshes for this CVE.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 14:16 UTCEPSS rescore
  3. 2026-07-23 01:59 UTCEG score recompute
  4. 2026-07-22 22:46 UTCEG score recompute
  5. 2026-07-22 21:04 UTCGHSA enrichment
  6. 2026-07-22 19:40 UTCCISA KEV update
  7. 2026-07-22 17:07 UTCEG score recompute
  8. 2026-07-22 17:07 UTCGHSA enrichment
  9. 2026-07-22 14:06 UTCEPSS rescore
  10. 2026-07-22 14:06 UTCEPSS rescore
  11. 2026-07-22 13:11 UTCGHSA enrichment
  12. 2026-07-22 09:15 UTCGHSA enrichment
  13. 2026-07-22 05:18 UTCGHSA enrichment
  14. 2026-07-22 01:21 UTCGHSA enrichment
  15. 2026-07-21 21:24 UTCGHSA enrichment
  16. 2026-07-21 17:27 UTCEG score recompute
  17. 2026-07-21 17:27 UTCGHSA enrichment
  18. 2026-07-21 15:22 UTCEPSS rescore
  19. 2026-07-21 15:22 UTCEPSS rescore
  20. 2026-07-21 14:37 UTCCISA KEV update
  21. 2026-07-21 13:31 UTCGHSA enrichment
  22. 2026-07-21 09:32 UTCGHSA enrichment
  23. 2026-07-21 05:35 UTCGHSA enrichment
  24. 2026-07-21 01:38 UTCGHSA enrichment
  25. 2026-07-20 21:42 UTCGHSA enrichment
Show 75 more
  1. 2026-07-20 17:45 UTCEG score recompute
  2. 2026-07-20 17:45 UTCGHSA enrichment
  3. 2026-07-20 17:05 UTCEPSS rescore
  4. 2026-07-20 13:49 UTCGHSA enrichment
  5. 2026-07-20 09:52 UTCGHSA enrichment
  6. 2026-07-20 05:56 UTCGHSA enrichment
  7. 2026-07-20 02:00 UTCGHSA enrichment
  8. 2026-07-19 22:03 UTCGHSA enrichment
  9. 2026-07-19 18:07 UTCGHSA enrichment
  10. 2026-07-19 14:11 UTCGHSA enrichment
  11. 2026-07-19 10:15 UTCGHSA enrichment
  12. 2026-07-19 06:18 UTCEG score recompute
  13. 2026-07-19 06:18 UTCGHSA enrichment
  14. 2026-07-19 02:27 UTCEPSS rescore
  15. 2026-07-19 02:27 UTCEPSS rescore
  16. 2026-07-19 02:21 UTCGHSA enrichment
  17. 2026-07-18 22:25 UTCGHSA enrichment
  18. 2026-07-18 18:29 UTCGHSA enrichment
  19. 2026-07-18 14:32 UTCGHSA enrichment
  20. 2026-07-18 10:36 UTCEG score recompute
  21. 2026-07-18 10:35 UTCGHSA enrichment
  22. 2026-07-18 10:02 UTCEPSS rescore
  23. 2026-07-18 10:02 UTCEPSS rescore
  24. 2026-07-18 06:38 UTCGHSA enrichment
  25. 2026-07-18 02:41 UTCGHSA enrichment
  26. 2026-07-17 22:45 UTCGHSA enrichment
  27. 2026-07-17 18:49 UTCGHSA enrichment
  28. 2026-07-17 14:52 UTCGHSA enrichment
  29. 2026-07-17 10:55 UTCGHSA enrichment
  30. 2026-07-17 06:58 UTCGHSA enrichment
  31. 2026-07-17 03:02 UTCGHSA enrichment
  32. 2026-07-16 23:06 UTCGHSA enrichment
  33. 2026-07-16 19:09 UTCGHSA enrichment
  34. 2026-07-16 17:04 UTCCISA KEV update
  35. 2026-07-16 17:00 UTCEPSS rescore
  36. 2026-07-16 15:13 UTCGHSA enrichment
  37. 2026-07-16 11:16 UTCGHSA enrichment
  38. 2026-07-16 07:20 UTCGHSA enrichment
  39. 2026-07-16 03:24 UTCGHSA enrichment
  40. 2026-07-15 23:28 UTCGHSA enrichment
  41. 2026-07-15 19:32 UTCGHSA enrichment
  42. 2026-07-15 16:55 UTCEPSS rescore
  43. 2026-07-15 16:55 UTCEPSS rescore
  44. 2026-07-15 16:49 UTCCISA KEV update
  45. 2026-07-15 15:35 UTCGHSA enrichment
  46. 2026-07-15 15:04 UTCCISA KEV update
  47. 2026-07-15 11:39 UTCGHSA enrichment
  48. 2026-07-15 07:42 UTCGHSA enrichment
  49. 2026-07-15 03:45 UTCGHSA enrichment
  50. 2026-07-15 01:58 UTCEPSS rescore
  51. 2026-07-14 23:49 UTCGHSA enrichment
  52. 2026-07-14 19:53 UTCGHSA enrichment
  53. 2026-07-14 18:05 UTCCISA KEV update
  54. 2026-07-14 15:56 UTCGHSA enrichment
  55. 2026-07-14 12:00 UTCGHSA enrichment
  56. 2026-07-14 08:04 UTCGHSA enrichment
  57. 2026-07-14 04:08 UTCGHSA enrichment
  58. 2026-07-14 00:11 UTCGHSA enrichment
  59. 2026-07-13 22:27 UTCEPSS rescore
  60. 2026-07-13 22:27 UTCEPSS rescore
  61. 2026-07-13 20:15 UTCGHSA enrichment
  62. 2026-07-13 17:07 UTCCISA KEV update
  63. 2026-07-13 16:18 UTCGHSA enrichment
  64. 2026-07-13 12:21 UTCGHSA enrichment
  65. 2026-07-13 08:24 UTCGHSA enrichment
  66. 2026-07-13 04:27 UTCGHSA enrichment
  67. 2026-07-13 00:31 UTCGHSA enrichment
  68. 2026-07-12 20:35 UTCGHSA enrichment
  69. 2026-07-12 16:38 UTCGHSA enrichment
  70. 2026-07-12 12:42 UTCGHSA enrichment
  71. 2026-07-12 08:45 UTCGHSA enrichment
  72. 2026-07-12 05:44 UTCEPSS rescore
  73. 2026-07-12 05:44 UTCEPSS rescore
  74. 2026-07-12 04:48 UTCGHSA enrichment
  75. 2026-07-12 00:52 UTCGHSA enrichment

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Metasploit module). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Metasploitexploit/multi/veritas/beagent_sha_auth_rce✓ verified
    First seen Mar 1, 2021

    Veritas Backup Exec Agent Remote Code Execution

    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2021-27876?
CVE-2021-27876 is a high vulnerability published on March 1, 2021. 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…
When was CVE-2021-27876 disclosed?
CVE-2021-27876 was first published in the National Vulnerability Database on March 1, 2021, with the most recent update on November 3, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-27876 actively exploited?
Yes. CISA added CVE-2021-27876 to the Known Exploited Vulnerabilities catalog on April 7, 2023, affecting Veritas Backup Exec Agent. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-27876?
CVE-2021-27876 has a CVSS v3 base score of 8.1 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-27876?
CVE-2021-27876 affects Veritas Backup Exec Agent. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-27876?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-27876, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2021-27876

Explore →

Is Your Infrastructure Affected by CVE-2021-27876?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs