CVE-2021-27876

CRITICALNVD 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
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 13%CVSS: 8.1Exploit: cisa kev · ssvc active · kev ransomware · Metasploit · epss top5pct · public exploitExposed: 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 PROB
13%
EPSS %ILE
96%
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 35× in last 7d / 224× 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 478 total refreshes for this CVE.

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

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 critical 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

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