CPANSA-YAML-Syck-2026-57075: YAML-Syck vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-07-16T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-07-16T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | 9.1 | Severity | |
| Original language | Language | en | |
| Also referred to | |||
Vulnerability Description
YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec. The base64 decoder in the bundled libsyck indexes the 256-entry static table b64_xtable with a signed char, so any !!binary byte >= 0x80 sign-extends to a negative index and reads before the table. The decoder receives the raw bytes of any !!binary node, a standard YAML type not gated by $LoadBlessed or $LoadCode, so it is reached on the default Load path. Any caller that runs Load or LoadFile on an untrusted document containing a !!binary scalar with a high-bit byte triggers the read, and the value read can surface in the decoded result.
Vulnerabilities
CVE-2026-57075
Vulnerability DescriptionYAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec.
The base64 decoder in the bundled libsyck indexes the 256-entry static table b64_xtable with a signed char, so any !!binary byte >= 0x80 sign-extends to a negative index and reads before the table. The decoder receives the raw bytes of any !!binary node, a standard YAML type not gated by $LoadBlessed or $LoadCode, so it is reached on the default Load path.
Any caller that runs Load or LoadFile on an untrusted document containing a !!binary scalar with a high-bit byte triggers the read, and the value read can surface in the decoded result.
| Weakness | CWE-125 : Out-of-bounds Read |
|---|
Product status
Known affected
| Product | Score | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| YAML-Syck less than 1.47 |
|
Fixed
- YAML-Syck greater than or equal 1.47
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA-YAML-Syck-2026-57075 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-yaml-syck-2026-57075.json - https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b.patch external
https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b.patch - https://metacpan.org/release/TODDR/YAML-Syck-1.47/changes external
https://metacpan.org/release/TODDR/YAML-Syck-1.47/changes - CVE-2026-57075 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-57075
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Thu Jul 16 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/