CVE-2019-25777: YAML versions before 1.27_001 for Perl allow a loaded perl/glob document to replace any package variable, which can lead to arbitrary code execution
Noroxi assessment
Priority: Monitor (action score 29/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.35% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: perl-YAML (AlmaLinux:8) 1.24-4.module_el8.10.0+4341+ab0ec422; libyaml-perl (Debian:12) 1.29-1; perl-YAML (openSUSE:Tumbleweed) 1.321.0-2.1.
Low priority for now. Upgrade to perl-YAML (AlmaLinux:8) 1.24-4.module_el8.10.0+4341+ab0ec422; libyaml-perl (Debian:12) 1.29-1; perl-YAML (openSUSE:Tumbleweed) 1.321.0-2.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
YAML versions before 1.27_001 for Perl allow a loaded perl/glob document to replace any package variable, which can lead to arbitrary code execution. A perl/glob document names a package and a symbol, and supplies the value assigned to it. Nothing restricts the name, so the target can be @INC or YAML's own load options. A perl/glob document that sets $YAML::LoadCode or $YAML::UseCode turns on code loading, which is off by default, for every later Load() in the process. A perl/code document is then passed to a string eval, so an attacker who supplies two documents to separate Load() calls in one process can execute arbitrary Perl code.
- Published
- Oct 5, 2026
- Updated
- Oct 6, 2026
- EPSS
- 0.3% · 29th percentile
- CWE
- CWE-502
Report tools
Action score
29
Low priority for now.
- CVSS
- 29 / 40 · 7.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (CPANSec). Independent of NVD's CPE analysis and usually ahead of it.
cpan.org/modules YAML
- before 1.27_001affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | perl-YAML | before 1.24-4.module_el8.10.0+4341+ab0ec422 | 1.24-4.module_el8.10.0+4341+ab0ec422 |
| Debian:12 | libyaml-perl | before 1.29-1 | 1.29-1 |
| openSUSE:Tumbleweed | perl-YAML | before 1.321.0-2.1 | 1.321.0-2.1 |
| Rocky Linux:8 | perl-YAML | before 0:1.24-4.module+el8.10.0+40403+9457ea6c | 0:1.24-4.module+el8.10.0+40403+9457ea6c |
| Rocky Linux:8 | perl-YAML | before 0:1.24-4.module+el8.10.0+40403+94558160 | 0:1.24-4.module+el8.10.0+40403+94558160 |
| Rocky Linux:8 | perl-YAML | before 0:1.24-4.module+el8.10.0+40403+bd06a93a | 0:1.24-4.module+el8.10.0+40403+bd06a93a |
| Rocky Linux:8 | perl-YAML | before 0:1.24-4.module+el8.10.0+40403+df14587c | 0:1.24-4.module+el8.10.0+40403+df14587c |
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| almalinux:perl-YAML | 1.24-4.module_el8.10.0+4341+ab0ec422 · AlmaLinux:8 | Package registry (OSV) |
| debian:libyaml-perl | 1.29-1 · Debian:12 | Package registry (OSV) |
| opensuse:perl-YAML | 1.321.0-2.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| rocky linux:perl-YAML | 0:1.24-4.module+el8.10.0+40403+bd06a93a · Rocky Linux:8 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- Fix recorded+1 d
- TodayNov 12, 2026+38 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Not on record for this CVE: researcher credit · variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- low · data or configuration can be modified
- Availability
- low · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- Low
- Availability impact
- Low
Weakness class (CWE)
CWE-502 · Deserialization of Untrusted DataCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
nvd-secondary
Root cause
Data received over the network is deserialized into the language’s native object format without verifying its source. Code paths inside the object can be triggered during deserialization.
The bug in code
The whole CWE-502 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
payload = sock.recv(65536)
job = pickle.loads(payload)Fixed
payload = sock.recv(65536)
if not hmac.compare_digest(sign(payload), header_sig):
raise PermissionError("invalid signature")
job = JobSchema.validate(json.loads(payload))Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
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Change log
- CVSS— → 7.3
- Severity— → high
- SSVC exploitation— → none
- Fix✗ → ✓
- Exploit maturity— → none
For records you follow, these changes also arrive as notifications. →
References
Show all references (3 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.