CVE-2021-28550

HIGHNVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 8.8 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
8.8
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 52%CVSS: 8.8Exploit: NoneExposed: 0

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

Acrobat Reader DC versions versions 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a Use After Free vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

CVSS v3
8.8
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
98.8%
KEV
⚠ Exploited

Published

September 2, 2021

Last Modified

October 23, 2025

Advisory Details (1)

Auto-updated Jun 2, 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-2021-28550

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 40× in last 7d / 207× 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 408 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2021-28550?
CVE-2021-28550 is a high vulnerability published on September 2, 2021. Acrobat Reader DC versions versions 2021.001.20150 (and earlier), 2020.001.30020 (and earlier) and 2017.011.30194 (and earlier) are affected by a Use After Free vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the…
When was CVE-2021-28550 disclosed?
CVE-2021-28550 was first published in the National Vulnerability Database on September 2, 2021, with the most recent update on October 23, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-28550 actively exploited?
Yes. CISA added CVE-2021-28550 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Adobe Acrobat and Reader. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-28550?
CVE-2021-28550 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-28550?
CVE-2021-28550 affects Adobe Acrobat and Reader. 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-2021-28550?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-28550, 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-2021-28550

Explore →

Is Your Infrastructure Affected by CVE-2021-28550?

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

Start Free Scan →Browse All CVEs