Cpanel JSON XS up to 4.79 Thaw decode_tag memory leak

Summaryinfo

A vulnerability, which was classified as critical, was found in Cpanel JSON XS up to 4.79. This impacts the function decode_tag of the component Thaw. The manipulation results in memory leak. This vulnerability was named CVE-2026-110685. The attack may be performed from remote. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Cpanel JSON XS up to 4.79. Affected is the function decode_tag of the component Thaw. The manipulation with an unknown input leads to a memory leak vulnerability. CWE is classifying the issue as CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Cpanel::JSON::XS versions before 4.80 for Perl leak the decoded arguments of a tagged value when its THAW method dies in decode_tag. With allow_tags, a tagged value's class name and argument array are decoded and passed to the class's THAW method. Both are released only after THAW returns, so a THAW that dies leaves the whole decoded argument structure allocated. Each rejected document leaks data of a size the sender chooses, so a process that catches the error and keeps running exhausts its memory.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-110685 since 10/14/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 4.80 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Hosting Control Software

Vendor

• Cpanel

Name

• JSON XS

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16
• 4.17
• 4.18
• 4.19
• 4.20
• 4.21
• 4.22
• 4.23
• 4.24
• 4.25
• 4.26
• 4.27
• 4.28
• 4.29
• 4.30
• 4.31
• 4.32
• 4.33
• 4.34
• 4.35
• 4.36
• 4.37
• 4.38
• 4.39
• 4.40
• 4.41
• 4.42
• 4.43
• 4.44
• 4.45
• 4.46
• 4.47
• 4.48
• 4.49
• 4.50
• 4.51
• 4.52
• 4.53
• 4.54
• 4.55
• 4.56
• 4.57
• 4.58
• 4.59
• 4.60
• 4.61
• 4.62
• 4.63
• 4.64
• 4.65
• 4.66
• 4.67
• 4.68
• 4.69
• 4.70
• 4.71
• 4.72
• 4.73
• 4.74
• 4.75
• 4.76
• 4.77
• 4.78
• 4.79

License

• commercial

CPE 2.3info

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CPE 2.2info

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