VulnSocial

CVE-2026-20293Disclosure

MEDIUMCVSS 7.1 · HIGH

Exploit discussion active in current signal (1 latest mentions)

Immediate actions

  • Patch affected systems immediately
  • Hunt for exploitation attempts and persistence artifacts
  • Increase monitoring for publicly documented tradecraft

Recommended action window: High priority (within 72h)

NVD description

A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers and UCS-based appliances could allow an authenticated attacker with valid credentials for a user account with the role of user or admin or an unauthenticated attacker with physical access to an affected device to bypass UEFI Secure Boot validation checks and execute unauthorized software. This vulnerability is due to the availability of memory write commands in the UEFI Shell while UEFI Secure Boot is enabled on a device. An attacker could exploit this vulnerability by selecting the UEFI Shell boot option at boot time and using available shell commands to modify UEFI memory variables. A successful exploit could allow the attacker to manipulate the preboot environment, overwrite UEFI Secure Boot-related memory values, and execute unauthorized software on the affected device.

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4.0/ 10 priority

Sources & remediation

Other references
Weakness type (CWE)
CWE-749

Priority

MEDIUM

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Threat summary

  • Public PoC and exploit tooling are both present
  • Patch or workaround signal is available
  • 4 mentions across 3 observed days
  • Momentum state: stable

What's happening

  • Exploit tool or code specified in 1 signal
  • PoC mentioned or linked in 3 signals
  • Patch or workaround mentioned in 3 signals
  • Technical details provided in 4 signals
  • Disclosure: 2 classified signals
  • Peaked 2d ago at 2 mentions (2026-09-08); latest day: 1
  • 4 total mentions across 3 days

Deep dive

Activity timeline4 mentions / 3d
01122Mentions · 2026-09-08: 2Mentions · 2026-09-09: 1Mentions · 2026-09-10: 1PoC Mentioned / Linked · 2026-09-08: 1PoC Mentioned / Linked · 2026-09-09: 1PoC Mentioned / Linked · 2026-09-10: 1Exploit Tool / Code · 2026-09-09: 1Patch / Workaround · 2026-09-08: 1Patch / Workaround · 2026-09-09: 1Patch / Workaround · 2026-09-10: 1Technical Details · 2026-09-08: 2Technical Details · 2026-09-09: 1Technical Details · 2026-09-10: 109-0809-0909-10
Signal classification2 categories
Disclosure
250.0%
PoC
250.0%
Referenced assets4 URLs
Classification over time
DateTotalLabels
2026-09-082
Disclosure2
2026-09-091
PoC1
2026-09-101
PoC1
Full discourse4 posts
  • Rıdvan Yağlı@ridvanyagli
    Disclosure

    🔴 Cisco UCS sunucularında Secure Boot bypass açığı! CVE-2026-20293, Cisco UCS sunucuları ve UCS tabanlı appliance'larda UEFI Secure Boot doğrulamasının atlatılmasına neden oluyor. Saldırgan, UEFI Shell üzerinden bellek üzerinde değişiklik yaparak güvenilmeyen yazılımların boot aşamasında çalıştırılmasını sağlayabiliyor. Açığın CVSS skoru 7.1 (High) ve Cisco, saldırının gerçekleştirilebilmesi için fiziksel erişim veya yetkili kullanıcı hesabı gerektiğini belirtiyor. Ayrıca PoC kodunun mevcut olduğu bildiriliyor. Cisco, açığın giderilmesi için etkilenen sistemlerin ilgili BIOS/firmware sürümlerine yükseltilmesini mutlaka öneriyor. resmi advisory: https://www.cisco.com/c/en/us/support/docs/csa/cisco-sa-ucs-uefi-sb-bypass-eb6xC5GW.html

    Post summary

    Cisco disclosed a UEFI Secure Boot bypass CVE‑2026‑20293 on UCS servers; PoC exists and a BIOS/firmware upgrade is required to remediate the vulnerability.

    00042491
    2.4K followersView on X
  • Xcademia@xcademialtd
    PoC

    🚨 Secure Boot isn’t so secure if attackers can rewrite memory before the OS even starts. Cisco disclosed CVE-2026-20293, a high-severity flaw affecting UEFI Shell implementations across Cisco UCS servers and appliances. ⚠️ CVSS 7.1 🔓 Secure Boot validation can be bypassed 💻 UEFI Shell memory commands are the root cause 🧪 Proof-of-concept exploit code is already available 🚫 No workaround is available 🛠️ Cisco has released fixes for affected platforms The bigger lesson: Firmware is part of your attack surface. Security controls protecting the operating system can't compensate for vulnerabilities hiding underneath it. If you run Cisco UCS, check your firmware and fixed release immediately. 🔗 https://www.xcademia.com/news/cisco-ucs-uefi-secure-boot-bypass-vulnerability-rated-high-poc-code-available #Cisco #Cybersecurity #SecureBoot #UEFI #FirmwareSecurity #CVE #Vulnerability #InfoSec #CyberSecurity #Xcademia

    Post summary

    Cisco disclosed a high‑severity UEFI Shell flaw (CVE‑2026‑20293) that allows Secure Boot validation to be bypassed; a PoC exploit exists, a patch is available, and no workaround exists.

    00020106
    22 followersView on X
  • NEXSIGHT@NEXSIGHTNEWS
    PoC

    Cisco UCSでSecure Bootバイパスの脆弱性 — UEFI Shellのメモリ書き込みで未署名コード実行、PoC公開済みで修正ファームウェア提供 https://cyber.nexsight.co/articles/2026/09/09/cisco-ucs-secure-boot-bypass-cve-2026-20293-2026-09-09/

    Post summary

    A Secure Boot bypass on Cisco UCS was disclosed with a publicly available proof of concept, and the vendor is providing patched firmware.

    0000062
    65 followersView on X
  • Kaitan ID Security@KaitanSecurity
    Disclosure

    ⚠️ HIGH — CVE-2026-20293 Cisco UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability CVSS 7.1 Full analysis → https://sec.kaitan.id/cves/CVE-2026-20293 #Cisco #CyberSecurity #InfoSec

    Post summary

    The post announces a high‑severity UEFI Secure Boot bypass (CVE‑2026‑20293) affecting Cisco UCS and UCS‑based appliances, providing a CVSS score of 7.1 and a link to a detailed analysis.

    0000064
    86 followersView on X

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