CVE-2026-13577
Dancer2 versions before 2.2.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable
Published Jul 20, 2026
CVSS 3.1 · 8.2 High
EPSS < 1%
KEV · Not listed
Description
Dancer2 versions before 2.2.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable.
Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id unless both Math::Random::ISAAC::XS and Crypt::URandom are available.
The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function).
These are all low-entropy and easily guessed sources.
The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications.
Predictable session ids could allow an attacker to gain access to systems.
Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id unless both Math::Random::ISAAC::XS and Crypt::URandom are available.
The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function).
These are all low-entropy and easily guessed sources.
The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications.
Predictable session ids could allow an attacker to gain access to systems.
Affected Products
-
CVE record
-
NVD configurations
No data
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Red Hat packages
No data
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OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| unaffected |
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No data.
No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cromedome | Dancer2 |
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Remediation
Vendor Solution
Upgrade to Davcer2 2.2.0 or later.
Vendor Workaround
For deployments that cannot upgrade, ensure Crypt::URandom and Math::Random::ISAAC::XS modules are installed in the application PERL5LIB path.
Tracking
Advisories
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity Low
Privileges Required None
Scope Unchanged
Confidentiality Impact Low
Integrity Impact None
Availability Impact High
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.570% probability within 30 days)
Exploitation none
Automatable yes
Technical Impact partial
References
History
Sep 20, 2026 10:30 AM
Description updated. Title updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id unless both Math::Random::ISAAC::XS and Crypt::URandom are available. The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function). These are all low-entropy and easily guessed sources. The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications. Predictable session ids could allow an attacker to gain access to systems. | Dancer2 versions before 2.2.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id unless both Math::Random::ISAAC::XS and Crypt::URandom are available. The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function). These are all low-entropy and easily guessed sources. The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications. Predictable session ids could allow an attacker to gain access to systems. |
| Title | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable | Dancer2 versions before 2.2.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable |
| References |
|
Jul 23, 2026 9:45 PM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Cromedome
Cromedome dancer2 |
|
| Vendors & Products |
Cromedome
Cromedome dancer2 |
Jul 22, 2026 12:15 PM
Description updated. Title updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id when both Math::Random::ISAAC::XS and Crypt::URandom are unavailable. The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function). These are all low-entropy and easily guessed sources. The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications. Predictable session ids could allow an attacker to gain access to systems. | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id unless both Math::Random::ISAAC::XS and Crypt::URandom are available. The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function). These are all low-entropy and easily guessed sources. The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications. Predictable session ids could allow an attacker to gain access to systems. |
| Title | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when CSPRNG modules are unavailable | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable |
Jul 20, 2026 1:30 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
Jul 20, 2026 8:15 AM
Description updated. Title updated. Weaknesses updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id when both Math::Random::ISAAC::XS and Crypt::URandom are unavailable. The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function). These are all low-entropy and easily guessed sources. The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications. Predictable session ids could allow an attacker to gain access to systems. | |
| Title | Dancer2 versions through 2.1.0 for Perl generate insecure session ids when CSPRNG modules are unavailable | |
| Weaknesses | CWE-338 CWE-340 |
|
| References |
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