VulnSocial

CVE-2026-16584Disclosure

LOWCVSS 7.3 · HIGH

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

Improper handling of an initialization failure in AWS API MCP Server from 0.2.13 through 1.3.46 might allow an actor to bypass the user-configured security policy and execute AWS API operations that the policy was set to deny or gate. When initialization of the security policy enforcement data fails at server startup, the policy check is skipped for the lifetime of the process. IAM permissions on the configured credentials remain in effect and are unaffected. To remediate this issue, users should upgrade to version 1.3.47.

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0.5/ 10 priority

Sources & remediation

Other references
Weakness type (CWE)
CWE-455

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

AVAILABLE

Momentum

STABLE

Threat summary

  • Patch or workaround signal is available
  • 6 mentions across 4 observed days
  • Momentum state: stable

What's happening

  • Patch or workaround mentioned in 3 signals
  • Technical details provided in 5 signals
  • Disclosure: 4 classified signals
  • Peaked 3d ago at 3 mentions (2026-07-23); latest day: 1
  • 6 total mentions across 4 days

Deep dive

Activity timeline6 mentions / 4d
01223Mentions · 2026-07-23: 3Mentions · 2026-07-27: 1Mentions · 2026-08-14: 1Mentions · 2026-10-04: 1Patch / Workaround · 2026-07-23: 2Patch / Workaround · 2026-07-27: 1Technical Details · 2026-07-23: 3Technical Details · 2026-07-27: 1Technical Details · 2026-08-14: 107-2307-2708-1410-04
Signal classification2 categories
Disclosure
480.0%
Patch
120.0%
Referenced assets4 URLs
Classification over time
DateTotalLabels
2026-07-233
Disclosure2Patch1
2026-07-271
Disclosure1
2026-08-141
Disclosure1
Full discourse6 posts
  • HOL@HashgraphOnline
    Disclosure

    AWS API MCP Server has a silent policy bypass (CVE-2026-16584). If the policy data fails to load at startup, enforcement is skipped with no error. Your agent then runs whatever it wants on AWS. Affects 0.2.13 to <1.3.47. Fixed in 1.3.47. https://hol.org/guard/security/unsafe-command

    Post summary

    AWS API MCP Server is vulnerable to a silent policy bypass (CVE‑2026‑16584); affected up to version 1.3.46 with patch available in 1.3.47. No PoC, exploit, or active exploitation is reported.

    21080596
    19.1K followersView on X
  • Tatiana Mikhaleva@DevOpsPink
    Patch

    In July, AWS fixed two read-only guardrails for AI agents in the same week. One skipped its deny list after a failed startup load (CVE-2026-16584). The other hid write tools but still ran them for anyone who knew the name. IAM held both times.

    Post summary

    AWS addressed two AI agent guardrail vulnerabilities in July, including CVE-2026-16584 (bypassing deny lists) and a flaw allowing hidden write tool execution. Both were fixed, with no mention of active exploitation or PoCs.

    1000029
    41 followersView on X
  • Lav Kumar Vishwakarma@LAV_K_V
    Disclosure

    AWS (@awscloud) credited me for CVE-2026-16584, a High-severity flaw in its API MCP Server. The server could appear healthy when its policy failed to load, skipping deny/gate checks. If policy isn’t ready, the server isn’t ready. https://lavkumar.dev/blog/cve-2026-16584-aws-api-mcp-server-security-bypass/ #MCP #AISecurity

    Post summary

    The tweet announces AWS's acknowledgment of CVE-2026-16584, a high‑severity flaw in its MCP Server that can bypass security checks when policies are not loaded.

    0001042
    27 followersView on X
  • Hugo | DevOps | Cybersecurity 🇱🇻@HugoValters
    Patch

    #CVE-2026-16584 - Security bypass in #AWS API MCP Server v0.2.13-1.3.46. Init failure skips user-configured policy checks, allowing unauthorized #AWS API ops. #CVSS 7.0. Update immediately. #CVEAlert #cybersecurity #devsecops #devops #infosec https://www.valtersit.com/cve/CVE-2026-16584

    Post summary

    The notice reveals a vulnerability in AWS API MCP Server versions v0.2.13-1.3.46 that bypasses policy checks, provides technical details and a CVSS score, and urges users to update immediately with an available patch.

    0000158
    989 followersView on X
  • Xavier Rivera@XavierRiveraX
    Disclosure

    AWS disclosed a security-policy bypass in its own API MCP Server: CVE-2026-16584, rated Important. If the server fails to start correctly, policy enforcement silently stays off for that process's life instead of blocking or erroring. Versions 0.2.13 through 1.3.46 are affected, fixed in 1.3.47. IAM permissions still apply, but any extra restriction the policy was meant to add just stops working, with no warning.

    Post summary

    AWS announced CVE‑2026‑16584, a security‑policy bypass in MCP Server that allows policies to be silently disabled, affecting versions 0.2.13–1.3.46, and the issue has been fixed in 1.3.47.

    0000089
    601 followersView on X
  • CVE@CVEnew
    Disclosure

    CVE-2026-16584 Improper handling of an initialization failure in AWS API MCP Server from 0.2.13 through 1.3.46 might allow an actor to bypass the user-configured security policy and… https://www.cve.org/CVERecord?id=CVE-2026-16584

    Post summary

    The text provides a brief technical overview of CVE‑2026‑16584, noting that improperly handled initialization failures in AWS API MCP Server could allow bypass of security policies, with no mention of PoC, exploitation, or fixes.

    00000812
    57.9K followersView on X

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