VulnerabilityPublished 25 Oct 2026Updated 2 Nov 2026

CVE-2026-115822: Starman versions before 0.4019 for Perl allow CPU exhaustion via quadratic regex backtracking when

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Authoritative record:CVE-2026-115822· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 0.4019 soon.

Data as of 2 Nov 2026, 17:13 UTC

CVSS 3.1 base score

7.5High

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

Thin evidence

One scorer or none

CVSS scores by source
CISA-ADP	CVSS 3.1	7.5

Patch: Available – fixed in 0.4019

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 25 Oct 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 2 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.

ghsa-2826-qw6w-9h42

What to do

Upgrade Starman (Perl module) to 0.4019.

Affected software

Product	Affected	Fixed in
Starman	Affected <0.4019	Fixed in 0.4019
CPANStarman`pkg:cpan/Starman`Other threats	Affected <0.4019	Fixed in 0.4019

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, consider implementing network-level protections such as rate limiting or filtering suspicious chunked requests to mitigate potential exploitation.

Description

Starman versions prior to 0.4019 for Perl contain a vulnerability where specially crafted chunked HTTP request bodies can cause CPU exhaustion due to quadratic regex backtracking. This occurs because the regex used to parse chunk-size lines does not properly handle lines with a bare LF followed by CRLF, leading to excessive backtracking and high CPU usage. An attacker can exploit this by sending such requests to any route, causing denial of service through resource exhaustion.

Impact

The vulnerability allows a remote attacker to cause denial of service by exhausting the CPU of Starman worker processes. This leads to degraded or unavailable service without requiring authentication or user interaction. The impact is limited to availability (denial of service) with no direct confidentiality or integrity effects reported.

Summary

Starman versions before 0.4019 for Perl are vulnerable to CPU exhaustion caused by quadratic regex backtracking when parsing chunked request bodies. The vulnerability arises from the regex pattern `s/^(([0-9a-fA-F]+).*\015\012)//` used to match chunk-size lines. This pattern fails to match lines with hex digits followed by a bare LF and then CRLF because the dot character does not match LF, resulting in repeated backtracking that grows quadratically with the length of the hex digits. There is no limit on the length of the line, allowing an attacker to craft requests that exhaust worker CPU resources remotely.

CWE-1333Inefficient Regular Expression Complexity (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Architecture and Design
Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
System Configuration
Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Implementation
Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
Regular Expression Exponential Blowup (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 2 Nov 2026, 17:13 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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