CVE-2026-126613VulnerabilityPublished 11 Nov 2026

Allocation of Resources Without Limits

Source GCVE Database

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Mentioned vulnerabilities

CVE-2026-107574

Authoritative record:CVE-2026-126613· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in 6.3.6 : patch hMailServer soon.

Data as of 11 Nov 2026, 10:05 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
CNA (GitLab)	CVSS 3.1	7.5

Patch: Available – fixed in 6.3.6

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 11 Nov 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 10 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-68qj-r5q8-pvm5

What to do

Affected software

Product	Affected	Fixed in
Progressive Robot LtdhMailServer	Affected >=6.3.2 <=6.3.7	Fixed in–
GitHubhmailserver/hmailserver`pkg:github/hmailserver/hmailserver`Other threats	Affected >=6.3.2 <=6.3.7	Fixed in–

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, disabling the REST API or restricting access to it may reduce exposure.

Description

A resource exhaustion vulnerability exists in the JSON reader of Progressive Robot hMailServer versions 6.3.2 through 6.3.7. A remote attacker can send specially crafted JSON documents that cause excessive memory allocation and thread blocking, leading to denial of service affecting mail delivery, the REST API, and webmail functionality. The vulnerability allows unauthenticated access via TLS-RPT reports and certain REST API endpoints when enabled. This flaw is distinct from another JSON reader issue fixed in version 6.3.6.

Impact

The vulnerability allows remote attackers to cause denial of service by exhausting server memory and blocking mail delivery threads. This results in unavailability of mail delivery, REST API, and webmail services. The attack can be performed without authentication via TLS-RPT reports and certain REST API endpoints when enabled, impacting availability but not confidentiality or integrity.

Summary

Progressive Robot hMailServer versions 6.3.2 through 6.3.7 contain a vulnerability in the JSON reader component that allows allocation of resources without limits. The reader builds a tree of values that can be far larger than the input text, copying each value into every level above it without bounding the number of values. This enables a remote attacker to exhaust server memory and hold mail delivery threads, making mail delivery, the REST API, and webmail unavailable. From version 6.3.4, unauthenticated attackers can exploit this via TLS-RPT reports or REST API endpoints if enabled. The REST API serves requests on four worker threads shared with SMTP, IMAP, and POP3, so multiple such requests can exhaust memory and cause service outages. This vulnerability is separate from CVE-2026-107574, which addresses duplicate member name handling and was fixed in 6.3.6.

CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Exponential Data Expansion (opens in a new tab)
Serialized Data Parameter Blowup (opens in a new tab)
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (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 11 Nov 2026, 10:05 UTC

WeaknessesCWE-770

Technical details

References

Community reviews

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