CVE-2021-35237

MEDIUMNVD 5.05.0—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.0 under NVD CVSS v3. EPSS exploit probability: 0.9%, top 43% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
5.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 5.0Exploit: None knownExposed: 0

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

A missing HTTP header (X-Frame-Options) in Kiwi Syslog Server has left customers vulnerable to click jacking. Clickjacking is an attack that occurs when an attacker uses a transparent iframe in a window to trick a user into clicking on an actionable item, such as a button or link, to another server in which they have an identical webpage. The attacker essentially hijacks the user activity intended for the original server and sends them to the other server. This is an attack on both the user and the server.

CVSS v3
5.0
EG Score
5.0(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

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
Severity50% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
57%
KEV
Not listed

Published

October 29, 2021

Last Modified

November 21, 2024

References (4)

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 43× 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 104 total refreshes for this CVE.

  1. 2026-07-26 14:52 UTCEPSS rescore
  2. 2026-07-26 14:52 UTCEPSS rescore
  3. 2026-07-25 14:15 UTCEPSS rescore
  4. 2026-07-23 14:16 UTCEPSS rescore
  5. 2026-07-23 14:16 UTCEPSS rescore
  6. 2026-07-23 02:02 UTCEG score recompute
  7. 2026-07-22 22:49 UTCEG score recompute▲ 0.70
  8. 2026-07-22 14:06 UTCEPSS rescore
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  1. 2026-07-11 08:25 UTCEPSS rescore
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  26. 2026-06-22 14:24 UTCEPSS rescore
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  28. 2026-06-21 14:55 UTCEPSS rescore
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  31. 2026-06-19 19:24 UTCEPSS rescore
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  35. 2026-06-17 17:51 UTCEPSS rescore
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  40. 2026-06-13 22:58 UTCEPSS rescore
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  42. 2026-06-12 23:10 UTCEPSS rescore
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  44. 2026-06-11 13:58 UTCEPSS rescore
  45. 2026-06-10 22:16 UTCEPSS rescore
  46. 2026-06-10 13:20 UTCEPSS rescore
  47. 2026-06-08 14:15 UTCEPSS rescore
  48. 2026-06-08 14:15 UTCEPSS rescore
  49. 2026-06-07 15:23 UTCEPSS rescore
  50. 2026-06-07 15:23 UTCEPSS rescore
  51. 2026-06-06 13:46 UTCEPSS rescore
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  54. 2026-06-05 22:45 UTCEPSS rescore
  55. 2026-06-05 06:09 UTCEPSS rescore
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  63. 2026-05-31 22:29 UTCEPSS rescore
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  71. 2026-05-27 13:39 UTCEPSS rescore
  72. 2026-05-27 13:39 UTCEPSS rescore
  73. 2026-05-27 13:39 UTCEPSS rescore
  74. 2026-05-26 13:42 UTCEPSS rescore
  75. 2026-05-26 08:18 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-35237?
CVE-2021-35237 is a medium vulnerability published on October 29, 2021. A missing HTTP header (X-Frame-Options) in Kiwi Syslog Server has left customers vulnerable to click jacking. Clickjacking is an attack that occurs when an attacker uses a transparent iframe in a window to trick a user into clicking on an actionable item, such as a button or link, to another server…
When was CVE-2021-35237 disclosed?
CVE-2021-35237 was first published in the National Vulnerability Database on October 29, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-35237 actively exploited?
CVE-2021-35237 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 43.1% of all scored CVEs.
What is the CVSS score of CVE-2021-35237?
CVE-2021-35237 has a CVSS v3 base score of 5.0 (NVD).
How do I remediate CVE-2021-35237?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-35237, 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.

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