CVE-2026-20355Patch

LOWCVSS 5.9 · MEDIUM

Signal is active with 1 mentions in latest observed window

Immediate actions

  • Patch affected systems immediately

Recommended action window: Monitor and triage in normal cycle

NVD description

Multiple vulnerabilities in the Secure/Multipurpose Internet Mail Extensions (S/MIME) decryption functionality of Cisco Secure Email could allow an unauthenticated, remote attacker to recover plain text from encrypted email messages. These vulnerabilities are due to insufficient validation of message integrity. An attacker could exploit these vulnerabilities by using a machine-in-the-middle technique to intercept and modify traffic between email gateways. A successful exploit could allow the attacker to obtain plaintext content from the encrypted communication.

0.5/ 10 priority

Sources & remediation

Weakness type (CWE)
CWE-345

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

AVAILABLE

Momentum

STABLE

Threat summary

  • Patch or workaround signal is available
  • 2 mentions across 2 observed days
  • Momentum state: stable

What's happening

  • Patch or workaround mentioned in 1 signal
  • General: 1 classified signal
  • Peaked 1d ago at 1 mentions (2026-09-03); latest day: 1
  • 2 total mentions across 2 days

Deep dive

Activity timeline2 mentions / 2d
00111Mentions · 2026-09-03: 1Mentions · 2026-09-07: 1Patch / Workaround · 2026-09-03: 109-0309-07
Signal classification2 categories
Patch
150.0%
General
150.0%
Referenced assets2 URLs
Classification over time
DateTotalLabels
2026-09-031
Patch1
2026-09-071
General1
Full discourse2 posts
  • SecurityWeek@SecurityWeek
    Patch

    Cisco Warns of Unpatched Secure Email Flaws, Patches Critical Switch Vulnerabilities (CVE-2026-20354 and CVE-2026-20355) - https://www.securityweek.com/cisco-warns-of-unpatched-secure-email-flaws-patches-critical-switch-vulnerabilities/

    Post summary

    Cisco announced and released patches for two critical Switch vulnerabilities (CVE‑2026‑20354 and CVE‑2026‑20355) while highlighting unpatched Secure Email flaws. No proof of concept, exploit, or active exploitation details are provided.

    0901044.8K
    229.0K followersView on X
  • セキュリティ対策Lab@securityLab_jp
    General

    Cisco Secure EmailにS/MIMEの脆弱性(CVE-2026-20354,CVE-2026-20355)、暗号化メールの平文取得につながる可能性 IP電話のDoSも公表 https://rocket-boys.co.jp/security-measures-lab/cisco-secure-email-smime-cve-incident/ #セキュリティ対策Lab #security #securitynews #セキュリティ #脆弱性

    Post summary

    The tweet announces two new CVEs (CVE‑2026‑20354 and CVE‑2026‑20355) affecting Cisco Secure Email S/MIME, highlighting a potential plaintext extraction and an IP‑phone DoS, but offers no technical depth, PoC, or patch details.

    00000150
    631 followersView on X

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