Bug 2555762 (CVE-2026-110678)

Summary: CVE-2026-110678 perl-Cpanel-JSON-XS: Memory exhaustion in incr_parse bypasses max_size
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in perl-Cpanel-JSON-XS. The parser appends each chunk to its buffer. In scalar or list context, it compares max_size with how far it has progressed, not with the total buffer length. A chunk that starts with a NUL byte stops the parser before it progresses, and a call in void context skips the check entirely, allowing the buffer to grow without limit. An attacker streaming data to an incr_parse consumer can exploit this to exhaust memory regardless of the max_size setting, resulting in a Denial of Service (DoS).
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Bug Depends On: 2556475, 2556476    
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Description OSIDB Bzimport 2026-10-19 18:36:12 UTC 
Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by buffering incremental input past max_size in incr_parse.

The parser appends each chunk to its buffer. In scalar or list context, it compares max_size with how far it has progressed, not with the buffer length. A chunk that starts with a NUL byte stops the parser before it progresses, and a call in void context skips the check, so the buffer grows without limit.

A peer streaming data to an incr_parse consumer can exhaust process memory regardless of max_size.