VulnerabilityPublished 22 Sep 2026

CVE-2026-93710: Dancer2 (Perl module) · Improper Cleanup on Thrown Exception

Affects Dancer2 (Perl module)Source CVE Database V5

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Not known to be exploited · CVSS 7.5 High : upgrade to 2.2.0 soon.

Data as of 5 Nov 2026, 23:24 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.2.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Dancer2 (Perl module) to 2.2.0.

Affected software

Product	Affected	Fixed in
CPANDancer2`pkg:cpan/Dancer2`Other threats	Affected >=2.0.0 <2.2.0	Fixed in 2.2.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, ensure that exception handlers properly halt the response by calling the halt method or setting the is_halted flag to prevent cleanup from discarding request state incorrectly. Avoid relying solely on the halt keyword without these explicit calls.

Description

CVE-2026-93710 affects Dancer2 versions from 2.0.0 up to but not including 2.2.0. It involves improper cleanup when an exception is thrown in a hook during request dispatch. Specifically, if an exception handler halts the response without properly invoking the halt method or setting the is_halted flag, cleanup does not prevent the refused route from running, potentially causing unintended request processing. This vulnerability has a high severity score of 7.5 due to its impact on availability.

Impact

The vulnerability can lead to unintended execution of refused routes, which may disrupt normal application flow and cause denial of service (availability impact). There is no direct confidentiality or integrity impact reported. The CVSS score of 7.5 reflects a high severity primarily due to the potential for availability disruption.

Summary

This vulnerability in Dancer2 (>=2.0.0 <2.2.0) relates to improper cleanup on thrown exceptions (CWE-460). When a hook dies, core.app.hook_exception is fired, and cleanup is called unless the failing hook is the exception handler. However, if the exception handler halts the response without properly calling the halt method or setting is_halted, cleanup discards the request, response, and session prematurely, allowing the refused route to execute. The issue arises because the halt keyword unwinds through with_return before cleanup runs, but a check in a before hook is not enforced, resulting in the route body running and its writes landing despite the refusal.

CWE-460Improper Cleanup on Thrown Exception (opens in a new tab)
Base weaknessLikelihood of exploit: MediumOWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product does not clean up its state or incorrectly cleans up its state when an exception is thrown.
Implementation
If one breaks from a loop or function by throwing an exception, make sure that cleanup happens or that you should exit the program. Use throwing exceptions sparsely.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Oct 2026, 23:05 UTC

WeaknessesCWE-460

Technical details

References

Community reviews

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