CVE-2026-11623Public exploit

Local server crash via wrong-list image unlink

Published Jun 9, 2026 · Updated Jun 9, 2026

Use-after-free in tmux 3.6a allows local users to crash the server by removing SIXEL images while an alternate screen is active. image_free unconditionally unlinks an image from the active image list after alternate-screen handling has moved that image to the saved list, corrupting list state before freeing it. Exploitation requires a local session, a build compiled with --enable-sixel, and crafted terminal input; upstream has demonstrated only a server crash.

CVSS severityUnavailable
Unscored
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in tmux 3.6a allows local users to crash the server by removing SIXEL images while an alternate screen is active. image_free unconditionally unlinks an image from the active image list after alternate-screen handling has moved that image to the saved list, corrupting list state before freeing it. Exploitation requires a local session, a build compiled with --enable-sixel, and crafted terminal input; upstream has demonstrated only a server crash.

The record

CVE
CVE-2026-11623
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
tmux
Product
tmux
Classifications
CWE-119, CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 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=3.6a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

tmux · tmuxversion=3.6a

Published CVSS scores

4.5VulDBCVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C
4.5VulDBCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C
2.0VulDBCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
3.5VulDBAV:L/AC:H/Au:S/C:P/I:P/A:P/E:POC/RL:OF/RC:C

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-416Use After Free
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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