CVE-2026-63729

Application crash and code execution via stale siblings

Published Jul 21, 2026 · Updated Jul 21, 2026

Heap use-after-free in TeX Live 2025 and earlier allows context-dependent attackers to crash applications or execute code via malformed SyncTeX files. In _synctex_post_process_ref, a parentless ref node remains linked to its live sibling chain, and recursive destruction frees nodes that later parser traversal dereferences. A crafted .synctex or .synctex.gz file must be processed during document loading; a crash is demonstrated, while arbitrary code execution is not publicly demonstrated.

CVSS severity6.8
Medium
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

Heap use-after-free in TeX Live 2025 and earlier allows context-dependent attackers to crash applications or execute code via malformed SyncTeX files. In _synctex_post_process_ref, a parentless ref node remains linked to its live sibling chain, and recursive destruction frees nodes that later parser traversal dereferences. A crafted .synctex or .synctex.gz file must be processed during document loading; a crash is demonstrated, while arbitrary code execution is not publicly demonstrated.

The record

CVE
CVE-2026-63729
Published
Jul 21, 2026
Updated
Jul 21, 2026
Vendor
TeX Users Group
Product
TeX Live
Classifications
CWE-416, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 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 <=TeX Live 2025

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

TeX Users Group · TeX Liveversion=0 <=TeX Live 2025

Published CVSS scores

6.6VulnCheckCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
6.6Red HatCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
6.8VulnCheckCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/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.

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

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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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