CVE-2021-27877

CRITICALNVD 8.29.8▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 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 8.2 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
8.2
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 65%CVSS: 8.2Exploit: 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. 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.

CVSS v3
8.2
EG Score
9.8(high)
EG Risk
99(Attend)
EG Risk 99/100SSVC: 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
Severity98% × 45%
Exploitation100% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
65%
EPSS %ILE
99%
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-2021-27877
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 41× in last 7d / 210× 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 421 total refreshes for this CVE.

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

Publicly available exploits

(3 references)

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 ↗
  • Nucleinetwork/cves/2021/CVE-2021-27877.yaml
    First seen Jan 1, 2021

    Veritas Backup Exec - Broken Authentication

    Open source ↗
  • Nucleijavascript/cves/2021/CVE-2021-27877.yaml
    First seen Jan 1, 2021

    Veritas Backup Exec - Broken Authentication

    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2021-27877?
CVE-2021-27877 is a high vulnerability published on March 1, 2021. 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…
When was CVE-2021-27877 disclosed?
CVE-2021-27877 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-2021-27877 actively exploited?
Yes. CISA added CVE-2021-27877 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-2021-27877?
CVE-2021-27877 has a CVSS v3 base score of 8.2 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.8.
Which products are affected by CVE-2021-27877?
CVE-2021-27877 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-2021-27877?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-27877, 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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