CVE-2026-124540

JSON::XS versions before 4.05 for Perl allow stack exhaustion via nested tagged values under allow_tags in decode_tag

Published Nov 14, 2026 CVSS n/a EPSS n/a KEV · Not listed
Description
JSON::XS versions before 4.05 for Perl allow stack exhaustion via nested tagged values under allow_tags in decode_tag.

With allow_tags, "(" starts a tagged value. Its tag and value are decoded recursively, and each can start another tagged value. Unlike arrays and objects, this nesting is not counted against max_depth.

A run of "(" bytes exhausts the C stack and triggers an uncatchable segmentation fault regardless of max_depth.

Remediation

Vendor Solution

Upgrade to JSON-XS 4.05 or later.

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History
Type Values Removed Values Added
Description JSON::XS versions before 4.05 for Perl allow stack exhaustion via nested tagged values under allow_tags in decode_tag. With allow_tags, "(" starts a tagged value. Its tag and value are decoded recursively, and each can start another tagged value. Unlike arrays and objects, this nesting is not counted against max_depth. A run of "(" bytes exhausts the C stack and triggers an uncatchable segmentation fault regardless of max_depth.
Title JSON::XS versions before 4.05 for Perl allow stack exhaustion via nested tagged values under allow_tags in decode_tag
Weaknesses CWE-674
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Weaknesses

Sources

Status
PUBLISHED
Assigner
CPANSec
Published
Updated
Nov 14, 2026, 11:52 AM
Reserved
Nov 8, 2026, 12:32 PM
Status
Received
Published
Nov 14, 2026, 12:17 PM
Modified
Nov 14, 2026, 12:17 PM