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Out-of-bounds ReadWeakness · CWE-125

CVE-2026-57075

CRITICAL · 9.1 CVSS v3.1 Published 2026-07-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

YAML::Syck versions before 1.47 contain an out-of-bounds read vulnerability in the base64 decoder (syck_base64dec). The decoder indexes a 256-entry lookup table (b64_xtable) using a signed char, so bytes with the high bit set (>= 0x80) sign-extend to negative indices, causing reads before the table. This is triggered by parsing untrusted YAML documents containing !!binary nodes with high-bit bytes.

MitigationUpgrade YAML::Syck to version 1.47 or later. If upgrade is not immediately possible, avoid loading untrusted YAML documents with !!binary nodes through Load/LoadFile functions.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if YAML::Syck is installed
    Run 'perl -MYAML::Syck -e "print $YAML::Syck::VERSION"' or inspect your project's dependency list for the YAML::Syck module
    Affected if YAML::Syck is present in the Perl environment
  2. Determine installed YAML::Syck version
    Compare the version output from step 1 against the vulnerable range: any version before 1.47 is affected
    Affected if Installed version is below 1.47
  3. Identify YAML document loading
    Search code for calls to YAML::Syck->Load, YAML::Syck::Load, or YAML::Syck::LoadFile that process input from untrusted sources
    Affected if Application loads YAML documents from untrusted sources
  4. Check for !!binary type processing
    Since !!binary is a standard YAML type processed by default on the Load path, any YAML containing binary data will trigger the vulnerable base64 decoder
    Affected if Untrusted YAML documents containing !!binary nodes are processed

If YAML::Syck version is below 1.47 AND your application loads untrusted YAML documents (which may contain !!binary nodes), the environment is affected by this out-of-bounds read vulnerability

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade YAML::Syck to version 1.47 or later. If upgrade is not immediately possible, avoid loading untrusted YAML documents with !!binary nodes through Load/LoadFile functions.

Recommended fix Moderate confidence

YAML::Syck version 1.47 or later

  1. Check the current version of YAML::Syck installed: perl -MYAML::Syck -e 'print $YAML::Syck::VERSION'
  2. Upgrade to version 1.47 or later using the cpan or cpanm tool: cpan YAML::Syck or cpanm YAML::Syck
  3. Verify the upgrade was successful by checking the version again
  4. Test any code that uses Load or LoadFile with YAML documents containing !!binary nodes to ensure correct behavior after the upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,540
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,464.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-57075 in production — separate from our analysis above.

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