CVE-2026-61674Public exploitNetwork attack vectorHinoki check available

Remote code execution via unchecked PONG reason copy

Published Sep 21, 2026 · Updated Sep 21, 2026

Stack buffer overflow in Fluent Bit 0.11.0 through 5.0.7 allows remote attackers to crash the agent or execute code via a crafted Secure Forward PONG. secure_forward_pong() copies the server-controlled PONG reason into a 32-byte stack buffer using its unchecked MessagePack type and length. The attacker must control or impersonate a configured Secure Forward destination; code execution requires a missing or disclosed canary, or opt-in supervisor mode for repeated crash-or-survive probes.

CVSS severity9.2
Critical
EPSS probability0.72%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Stack buffer overflow in Fluent Bit 0.11.0 through 5.0.7 allows remote attackers to crash the agent or execute code via a crafted Secure Forward PONG. secure_forward_pong() copies the server-controlled PONG reason into a 32-byte stack buffer using its unchecked MessagePack type and length. The attacker must control or impersonate a configured Secure Forward destination; code execution requires a missing or disclosed canary, or opt-in supervisor mode for repeated crash-or-survive probes.

The record

CVE
CVE-2026-61674
Published
Sep 21, 2026
Updated
Sep 21, 2026
Vendor
Fluent Bit
Product
Fluent Bit
Classifications
CWE-121, CWE-843, CWE-787, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.11.0, < 5.0.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fluent Bit · Fluent Bitversion=>= 0.11.0, < 5.0.8

Published CVSS scores

9.2GitHub Security AdvisoryCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
CWE-787Out-of-bounds Write
T1059Command and Scripting Interpreter

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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