Vulnerability · Published Jul 16, 2026 · Assigned by CPANSec
CVE-2026-57075YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec
Critical 9.1
In plain English
A critical-severity out-of-bounds read in YAML::Syck from TODDR. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | perl-yaml-syck | 1.47-r0 | ALPINE-CVE-2026-57075 |
| Debian:12 | libyaml-syck-perl | 1.34-2+deb12u3 | DEBIAN-CVE-2026-57075 |
| Debian:13 | libyaml-syck-perl | 1.34-2+deb13u3 | DEBIAN-CVE-2026-57075 |
| Debian:14 | libyaml-syck-perl | 1.47-1 | DEBIAN-CVE-2026-57075 |
| Ubuntu:26.04:LTS | libyaml-syck-perl | no fix listed | UBUNTU-CVE-2026-57075 |
| Ubuntu:26.10 | libyaml-syck-perl | no fix listed | UBUNTU-CVE-2026-57075 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| TODDR | YAML::Syck | 0 – before 1.47 |
Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H