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VulnerabilityPublished

CVE-2026-124541: JSON::XS versions before 4.05 for Perl leak the decoded part of a rejected long string in decode_str

Source GCVE Database

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Authoritative record:CVE-2026-124541· Medium

Not known to be exploited : upgrade to 4.05 when convenient.

Data as of 14 Nov 2026, 13:17 UTC

Severity
Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none
Patch
Available – fixed in 4.05

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 14 Nov 2026.

What to do

Upgrade JSON-XS (Perl module) to 4.05.

Affected software

ProductAffectedFixed in
JSON-XSAffected
  • <4.05
Fixed in
  • 4.05
CPANJSON-XSpkg:cpan/JSON-XSOther threatsAffected
  • <4.05
Fixed in
  • 4.05

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

AI-suggested

A fix is available in JSON::XS version 4.05 and later. Users should upgrade to version 4.05 or newer to resolve this memory leak issue. No other mitigation is indicated.

Description

JSON::XS versions before 4.05 for Perl contain a vulnerability in the decode_str function where rejected long strings leak decoded data. This occurs because decoded string parts are stored in fixed-size buffers that are not freed upon rejection due to control characters, invalid escapes, malformed UTF-8, or premature end of input. A process that continues running after such failed decodes retains these leaked string parts, potentially exhausting memory over repeated requests.

References

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