VulnerabilityPublished 19 Oct 2026Updated 29 Oct 2026

CVE-2026-110688: Cpanel::JSON::XS versions from 4.51 before 4.80 for Perl allow quadratic CPU use by revalidating the

Source GCVE Database

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Authoritative record:CVE-2026-110688· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 4.80 soon.

Data as of 29 Oct 2026, 20:15 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CISA-ADP	CVSS 3.1	7.5

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.80

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-cv8j-jrx6-q4fj

What to do

Upgrade Cpanel-JSON-XS (Perl module) to 4.80.

Affected software

Product	Affected	Fixed in
Cpanel-JSON-XS	Affected >=4.51 <4.80	Fixed in 4.80
CPANCpanel-JSON-XS`pkg:cpan/Cpanel-JSON-XS`Other threats	Affected >=4.51 <4.80	Fixed in 4.80

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fixed version of Cpanel::JSON::XS is available starting from version 4.80. Users should upgrade to version 4.80 or later to remediate this vulnerability. No other mitigation or temporary workaround is indicated.

Description

Cpanel::JSON::XS versions from 4.51 up to but not including 4.80 for Perl contain a vulnerability that causes quadratic CPU usage during JSON parsing. This occurs because the decoder revalidates the remaining buffer for each value, leading to excessive CPU consumption when processing non-ASCII JSON data. A large input of about one megabyte of non-ASCII JSON can cause the process to be tied up for several seconds.

Impact

This vulnerability can lead to high CPU usage and potential denial of service conditions when processing specially crafted JSON inputs containing non-ASCII characters. The CPU consumption grows quadratically with input size, meaning that large inputs can tie up system resources for extended periods, impacting availability.

Summary

The vulnerability in Cpanel::JSON::XS versions from 4.51 before 4.80 arises from the incr_parse function, which revalidates the remaining input buffer for each JSON value parsed. At the first non-ASCII byte, the UTF-8 decoder validates from that point to the end of the input. Since each buffered value is decoded with a fresh decoder, this results in quadratic CPU usage relative to input size. An attacker can exploit this by sending a large JSON payload with non-ASCII characters, causing significant CPU resource consumption and potential denial of service.

CWE-407Inefficient Algorithmic Complexity (opens in a new tab)
Class weaknessLikelihood of exploit: Low
An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Oct 2026, 20:15 UTC

WeaknessesCWE-407

Technical details

References

Community reviews

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