CVE-2026-16634 (CVSS 9.8)

Description

TOML::XS versions before 0.06 for Perl bundle an unsupported and vulnerable version of tomlc99. The tomlc99 library is no longer maintained, and has an uncontrolled recursion vulnerability publicly reported in the issue tracker. Any caller that passes untrusted TOML to from_toml risks a stack overflow from a deeply-nested document. TOML::XS version 0.06 or later uses the successor tomlc17 library.

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CVSS v3.1 Score

9.8

CRITICAL

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

EPSS — Exploit Prediction

0.0077

Probability of exploitation

0.52%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1104 CWE-1104

References

Other References

https://github.com/cktan/tomlc17 https://github.com/cktan/tomlc99/issues/97 https://metacpan.org/release/FELIPE/TOML-XS-0.06/changes https://raw.githubusercontent.com/cktan/tomlc99/29076dfd095bbbbd50a3c1b2760d29f4b83e74ac/README.md https://toml.io/en/v1.0.0 http://www.openwall.com/lists/oss-security/2026/07/24/4 https://github.com/cktan/tomlc99/issues/97

Frequently Asked Questions

What is CVE-2026-16634? +

TOML::XS versions before 0.06 for Perl bundle an unsupported and vulnerable version of tomlc99. The tomlc99 library is no longer maintained, and has an uncontrolled recursion vulnerability publicly reported in the issue tracker. Any caller that passes untrusted TOML to from_toml risks a stack overflow from a deeply-nested document. TOML::XS version 0.06 or later uses the successor tomlc17 library. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-16634? +

CVE-2026-16634 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0077, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-16634? +

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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