CVE-2026-20121

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 5.3 from GitHub Security Advisory published 2026-09-16. The CNA's CVSS baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: the CNA's CVSS, EPSS, GitHub Security Advisory

Also known asEUVD-2026-81017 (ENISA EUVD) · GHSA-9j5c-2gxv-8m6x (GitHub Security Advisories)Source: ENISA EUVD

5.3EG
EchelonGraph verdictMonitorNo fix is confirmed yet: check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 5.3Exploit: None knownExposed services: Not assessed

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

A vulnerability in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured access controls. This vulnerability is due to a logic error in populating group access control policies (ACPs) with OGS configured. An attacker could exploit this vulnerability by sending traffic that should be blocked through the device. A successful exploit could allow the attacker to bypass access controls and reach devices in protected networks.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
43rd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule 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). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

September 16, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Sep 16, 2026
No fix on record yet.
Web page

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Object Group Access Control List Bypass Vulnerabilities

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-acl-bypass-8p6vFvw

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 52× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  2. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  3. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  4. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  5. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  6. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  7. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  8. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  9. 2026-10-25 14:44 UTCEG score recompute
  10. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  11. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  12. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  13. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  14. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  15. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  16. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  17. 2026-10-18 03:57 UTCEG score recompute
  18. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  19. 2026-10-16 21:57 UTCEG score recompute
  20. 2026-10-16 21:57 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  21. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  22. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  23. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  24. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  25. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
Show 72 more
  1. 2026-10-12 16:24 UTCEG score recompute
  2. 2026-10-11 19:53 UTCEG score recompute
  3. 2026-10-11 19:53 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  4. 2026-10-11 17:19 UTCEG score recompute
  5. 2026-10-11 14:51 UTCEG score recompute
  6. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  7. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  8. 2026-10-10 17:39 UTCEG score recompute
  9. 2026-10-10 17:39 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  10. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  11. 2026-10-09 15:22 UTCEG score recompute
  12. 2026-10-09 15:22 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  13. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  14. 2026-10-08 12:31 UTCEG score recompute
  15. 2026-10-08 12:31 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  16. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  17. 2026-10-07 10:00 UTCEG score recompute
  18. 2026-10-07 10:00 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  19. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  20. 2026-10-06 07:46 UTCEG score recompute
  21. 2026-10-06 07:46 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  22. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  23. 2026-10-05 05:33 UTCEG score recompute
  24. 2026-10-05 05:33 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  25. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  26. 2026-10-04 03:19 UTCEG score recompute
  27. 2026-10-04 03:19 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  28. 2026-10-03 01:05 UTCEG score recompute
  29. 2026-10-03 01:05 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  30. 2026-10-01 22:52 UTCEG score recompute
  31. 2026-10-01 22:52 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  32. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  33. 2026-09-30 20:39 UTCEG score recompute
  34. 2026-09-30 20:38 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  35. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  36. 2026-09-29 18:24 UTCEG score recompute
  37. 2026-09-29 18:24 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  38. 2026-09-29 15:21 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  39. 2026-09-28 15:37 UTCEG score recompute
  40. 2026-09-28 15:37 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  41. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  42. 2026-09-27 13:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  43. 2026-09-27 13:13 UTCEG score recompute
  44. 2026-09-27 13:13 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  45. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  46. 2026-09-26 11:00 UTCEG score recompute
  47. 2026-09-26 10:59 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  48. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  49. 2026-09-25 08:41 UTCEG score recompute
  50. 2026-09-25 08:41 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  51. 2026-09-24 14:03 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  52. 2026-09-24 06:27 UTCEG score recompute
  53. 2026-09-24 06:27 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  54. 2026-09-23 04:14 UTCEG score recompute
  55. 2026-09-23 04:14 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  56. 2026-09-22 02:00 UTCEG score recompute
  57. 2026-09-22 02:00 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  58. 2026-09-20 23:47 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  59. 2026-09-19 21:33 UTCEG score recompute
  60. 2026-09-19 21:33 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  61. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  62. 2026-09-18 19:20 UTCEG score recompute
  63. 2026-09-18 19:20 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  64. 2026-09-18 13:40 UTCEG score recompute
  65. 2026-09-18 13:40 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  66. 2026-09-17 17:59 UTCEG score recompute
  67. 2026-09-17 17:59 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  68. 2026-09-17 16:04 UTCEG score recompute
  69. 2026-09-17 16:04 UTCGHSA enrichmentGHSA-9j5c-2gxv-8m6x · GitHub CVSS 5.3
  70. 2026-09-16 21:25 UTCEG score recompute
  71. 2026-09-16 20:41 UTCEG score recomputeFirst assessed: 5.3 MEDIUM
  72. 2026-09-16 20:34 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-20121?
CVE-2026-20121 is a medium-severity vulnerability; its CVE record was published on September 16, 2026. A vulnerability in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured access controls.…
When was the CVE record for CVE-2026-20121 published?
The CVE record for CVE-2026-20121 was published on September 16, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 18, 2026; the record at its source may have been updated since.
Is CVE-2026-20121 actively exploited?
CVE-2026-20121 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (43rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-20121?
CVE-2026-20121 has a CVSS base score of 5.3 (the CNA's own assessment, by cisco; NVD's own analysis pending).
How do I remediate CVE-2026-20121?
No fix for CVE-2026-20121 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-20121 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-20121

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