CVE-2021-34749

HIGHNVD 5.88.6▲
EchelonGraph scoreMEDIUM confidence

Score 8.6 from GitHub Security Advisory (severity: HIGH) published 2022-05-24. NVD baseline CVSS 5.8; sources differ by 2.8.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.6EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1.7%CVSS: 5.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A vulnerability in Server Name Identification (SNI) request filtering of Cisco Web Security Appliance (WSA), Cisco Firepower Threat Defense (FTD), and the Snort detection engine could allow an unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data from a compromised host. This vulnerability is due to inadequate filtering of the SSL handshake. An attacker could exploit this vulnerability by using data from the SSL client hello packet to communicate with an external server. A successful exploit could allow the attacker to execute a command-and-control attack on a compromised host and perform additional data exfiltration attacks.

CVSS v3
5.8
EG Score
8.6HIGHmedium confidence
EG Risk
54
EG Risk 54/100CISA SSVC

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
Severity86% × 45%
Exploitation2% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
1.7%
EPSS %ILE
76th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 18, 2021

Last Modified

November 26, 2024

References (6)

Affected Packages

(2 across 2 ecosystems)
Debian:10(1)
PackageVulnerable rangeFix by version rangeDependents
snort2.9.15.1-1 ... 2.9.7.0-5 (7 versions)
  • every version up to 2.9.20-0+deb10u1: fixed in 2.9.20-0+deb10u1
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
snort2.9.15.1-5, 2.9.15.1-6
  • every version up to 2.9.20-0+deb11u1: fixed in 2.9.20-0+deb11u1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 31× 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 174 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2021-34749?
CVE-2021-34749 is a high vulnerability published on August 18, 2021. A vulnerability in Server Name Identification (SNI) request filtering of Cisco Web Security Appliance (WSA), Cisco Firepower Threat Defense (FTD), and the Snort detection engine could allow an unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data…
When was CVE-2021-34749 disclosed?
CVE-2021-34749 was first published on August 18, 2021, with the most recent update on November 26, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-34749 actively exploited?
CVE-2021-34749 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.7% probability of exploitation in the next 30 days (76th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-34749?
CVE-2021-34749 has a CVSS v3 base score of 5.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.6 (HIGH).
How do I remediate CVE-2021-34749?
A fix for CVE-2021-34749 is available: update to the fixed version the vendor names in its advisory.

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