CVE-2026-124536: DoS

Description

JSON::XS versions before 4.05 for Perl allow memory exhaustion by buffering incremental input past max_size after a NUL byte in incr_parse. The parser appends each chunk to its buffer and compares max_size with how far it has progressed, not with the buffer length. It treats a NUL byte as the end of the input, so a NUL within the first max_size bytes keeps it short of the limit. The buffer keeps growing, and incr_skip cannot remove the NUL. A peer streaming data to an incr_parse consumer can exhaust process memory regardless of max_size.

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Weakness Type (CWE)

CWE-770 CWE-770

References

Other References

https://metacpan.org/release/MLEHMANN/JSON-XS-4.05/changes

Frequently Asked Questions

What is CVE-2026-124536? +

JSON::XS versions before 4.05 for Perl allow memory exhaustion by buffering incremental input past max_size after a NUL byte in incr_parse. The parser appends each chunk to its buffer and compares max_size with how far it has progressed, not with the buffer length. It treats a NUL byte as the end of the input, so a NUL within the first max_size bytes keeps it short of the limit. The buffer keeps growing, and incr_skip cannot remove the NUL. A peer streaming data to an incr_parse consumer can exhaust process memory regardless of max_size.

How do I check if I'm vulnerable to CVE-2026-124536? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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