CVE-2021-4461

CRITICALNVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under NVD CVSS v3. EPSS exploit probability: 0.6%, top 55% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
9.3
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.3Exploit: NoneExposed: 0

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

Seeyon Zhiyuan OA Web Application System versions up to and including 7.0 SP1 improperly decode and parse the enc parameter in thirdpartyController.do. The decoded map values can influence session attributes without sufficient authentication/authorization checks, enabling attackers to assign a session to arbitrary user IDs. VulnCheck has observed this vulnerability being exploited in the wild as of 2025-10-30 at 00:30:40.855917 UTC.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
57(Track)
EG Risk 57/100SSVC: 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
Severity93% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
45.2%
KEV
Not listed

Published

October 30, 2025

Last Modified

April 15, 2026

Advisory Details (4)

Auto-updated Jul 16, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic🔴 Active Exploitation

Seeyon Zhiyuan OA Web Application System < 7.0 SP1 Authentication Bypass | Advisories | VulnCheck

https://www.vulncheck.com/advisories/seeyon-zhiyuan-oa-web-application-system-authentication-bypass
generic
https://mp.weixin.qq.com/s/0AqdfTrZUVrwTMbKEKresg
generic

nuclei-templates/http/misconfiguration/seeyon-unauth.yaml at 1ca6b8e6fe225cbd46dcb893dcaee01447afa8c0 · projectdiscovery/nuclei-templates · GitHub

https://github.com/projectdiscovery/nuclei-templates/blob/1ca6b8e6fe225cbd46dcb893dcaee01447afa8c0/http/misconfiguration/seeyon-unauth.yaml#L20
generic

xray/pocs/seeyon-oa-cookie-leak.yml at f90cf321bc4d294bbf6625a9c4853f3bfdf0a384 · chaitin/xray · GitHub

https://github.com/chaitin/xray/blob/f90cf321bc4d294bbf6625a9c4853f3bfdf0a384/pocs/seeyon-oa-cookie-leak.yml

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 47× 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 140 total refreshes for this CVE.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-24 14:15 UTCEPSS rescore
  3. 2026-07-23 14:16 UTCEPSS rescore
  4. 2026-07-23 02:05 UTCEG score recompute
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  1. 2026-07-08 15:12 UTCEPSS rescore
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  45. 2026-06-10 22:16 UTCEPSS rescore
  46. 2026-06-10 13:20 UTCEPSS rescore
  47. 2026-06-08 15:20 UTCEG score recompute▲ 9.30
  48. 2026-06-08 15:20 UTCGHSA enrichment
  49. 2026-06-08 14:15 UTCEPSS rescore
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  75. 2026-05-26 13:42 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2021-4461?
CVE-2021-4461 is a critical vulnerability published on October 30, 2025. Seeyon Zhiyuan OA Web Application System versions up to and including 7.0 SP1 improperly decode and parse the enc parameter in thirdpartyController.do. The decoded map values can influence session attributes without sufficient authentication/authorization checks, enabling attackers to assign a…
When was CVE-2021-4461 disclosed?
CVE-2021-4461 was first published in the National Vulnerability Database on October 30, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-4461 actively exploited?
CVE-2021-4461 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 45.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-4461?
CVE-2021-4461 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2021-4461?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-4461, 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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