CVE-2026-123660VulnerabilityPublished 6 Nov 2026

In Vulnerability-Lookup 5.5.1 up to but not including 6.4.1, a signed-in user could make the server allocate memory

Source GCVE Database

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Authoritative record:CVE-2026-123660· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium : upgrade to 6.4.1 when convenient.

Data as of 6 Nov 2026, 10:34 UTC

CVSS 4.0 base score

5.3Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (CIRCL)	CVSS 4.0	5.3

Patch: Available – fixed in 6.4.1

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 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 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.

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What to do

Upgrade vulnerability-lookup and vulnerability-lookup/vulnerability-lookup to 6.4.1.

Affected software

Product	Affected	Fixed in
vulnerability-lookupvulnerability-lookup	Affected >=5.5.1 <6.4.1	Fixed in 6.4.1
GitHubvulnerability-lookup/vulnerability-lookup`pkg:github/vulnerability-lookup/vulnerability-lookup`Other threats	Affected >=5.5.1 <6.4.1	Fixed in 6.4.1

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

AI-suggested

Upgrade to Vulnerability-Lookup version 6.4.1 or later, which implements caps on format specifier sizes, limits on rendered template length, and nesting depth restrictions to prevent excessive memory allocation and recursion errors. These mitigations effectively address the vulnerability. No additional action is required if already running version 6.4.1 or newer.

Description

Vulnerability-Lookup versions 5.5.1 up to but not including 6.4.1 contain a flaw where signed-in users can cause excessive memory allocation via webhook notification payload templates. The issue arises because format specifiers in placeholders are passed directly to Python's string formatting, allowing creation of very large strings. This can lead to denial of service by exhausting memory resources of web workers or the notification daemon. Version 6.4.1 introduces limits on format specifier sizes, template length, and nesting depth to mitigate the issue.

Impact

An attacker with a valid account can cause denial of service by exhausting memory resources of the server's web workers or notification daemon through crafted webhook notification payload templates. This can disrupt normal operation and availability of the Vulnerability-Lookup service. The vulnerability does not require elevated privileges beyond a signed-in user account.

Summary

In Vulnerability-Lookup versions from 5.5.1 up to but excluding 6.4.1, a signed-in user can exploit the webhook notification payload template processing to cause the server to allocate memory disproportionately large relative to their input. This occurs because each placeholder's format specifier is passed unchanged to Python's string formatting, which constructs the padded string before size validation. For example, a template with a format specifier like {"text": "{title:>999999999}"} can produce a string approximately 1 GB in size during test rendering on save. Repeating such placeholders multiplies memory consumption. Additionally, deeply nested templates cause unhandled recursion errors resulting in HTTP 500 responses. An attacker only requires an account, which default configurations allow creation of after email confirmation, to trigger this denial of service condition. Version 6.4.1 mitigates the vulnerability by capping format specifier numbers at 256, limiting rendered template size to 1,000,000 characters on save and delivery, and rejecting templates nested deeper than 32 levels.

CWE-674Uncontrolled Recursion (opens in a new tab)
Class weakness
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Implementation
Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation
Increase the stack size.
Attack patterns
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 6 Nov 2026, 10:34 UTC

WeaknessesCWE-674

Technical details

References

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