CVE-2026-61674: Fluent Bit is a fast and lightweight logs, metrics, and traces processor for Linux, BSD, macOS, and Windows

This month

CRITICAL 9.2REMOTEWATCHLIST

CVE-2026-61674 is a critical-severity flaw (CVSS 9.2) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Fluent Bit is a fast and lightweight logs, metrics, and traces processor for Linux, BSD, macOS, and Windows. From 0.11.0 until 5.0.8, plugins/out_forward/forward.c secure_forward_pong copies the server-controlled PONG[2] reason into the 32-byte stack buffer msg with memcpy without checking its MessagePack type or length. An attacker who controls or can impersonate an out_forward Secure Forward destination configured with Shared_Key or Empty_Share

Why this priority

Critical severity
CISA SSVC: public proof of concept
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.2 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-121, CWE-787, CWE-843
Published	2026-09-21
Last modified	2026-09-24

Publisher (CNA): GitHub, Inc.

Last updated 2026-09-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-09-21 17:17 UTCPublished CVE record published
2026-09-24 21:16 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · fio · FIXED · 3.43-2.fc46 · FEDORA-2026-b36219886b · source

sudo dnf upgrade --advisory=FEDORA-2026-b36219886b

Fedora ELN · weston · FIXED · 16.0.2-1.eln159 · FEDORA-2026-b98ccaa6a0 · source

sudo dnf upgrade --advisory=FEDORA-2026-b98ccaa6a0

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/fluent/fluent-bit/security/advisories/GHSA-jrp8-r9hx-gf73

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-61674?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-61674 being exploited?

CVE-2026-61674 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-61674 affect?

CVE-2026-61674 affects affected software. Severity is critical (CVSS 9.2). Fluent Bit is a fast and lightweight logs, metrics, and traces processor for Linux, BSD, macOS, and Windows. From 0.11.0 until 5.0.8, plugins/out_forward/forward.c secure_forward_pong copies the server-controlled PONG[2] reason into the 32-

How urgent is CVE-2026-61674?

Priority 59/100. Critical severity; CISA SSVC: public proof of concept; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Windows vulnerabilities · macOS vulnerabilities

References

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