VulnerabilityPublished 28 Oct 2026

CVE-2026-116273: MIME::Parser versions before 5.521 for Perl set no limit on the number of message parts by default

Source GCVE Database

Authoritative record:CVE-2026-116273· High

Not known to be exploited : upgrade to 5.521 soon.

Data as of 28 Oct 2026, 19:29 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Patch: Available – fixed in 5.521

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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-xrpv-r4cr-x2x4

What to do

Upgrade MIME-tools (Perl module) to 5.521.

Affected software

Product	Affected	Fixed in
MIME-tools	Affected <5.521	Fixed in 5.521
CPANMIME-tools`pkg:cpan/MIME-tools`Other threats	Affected <5.521	Fixed in 5.521

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

AI-suggested

Upgrade to MIME::Parser version 5.521 or later, which sets safe default limits on max_parts and max_depth. If upgrading is not immediately possible, manually configure max_parts and max_depth to reasonable limits to prevent memory exhaustion. Setting these options to -1 disables limits and is not recommended.

Description

MIME::Parser versions before 5.521 for Perl do not limit the number of message parts by default, which can lead to memory exhaustion. The default max_parts option was set to -1, disabling limits and allowing a parser to build entities for every message part regardless of quantity. Version 5.521 introduces default limits of max_parts to 1000 and max_depth to 64, mitigating this issue. Users can still disable these limits by setting these options to -1.

Impact

Unbounded processing of message parts can lead to memory exhaustion on systems using vulnerable MIME::Parser versions, potentially causing denial of service due to resource depletion. There is no indication of remote code execution or data corruption from the provided data.

Summary

The vulnerability in MIME::Parser for Perl (before version 5.521) arises because the max_parts option defaulted to -1, effectively disabling any limit on the number of message parts processed. This behavior allows an attacker to craft messages with an excessive number of parts, causing the parser to consume excessive memory and potentially exhaust system resources. Version 5.521 addresses this by setting default limits on max_parts (1000) and max_depth (64), preventing unbounded resource consumption unless explicitly overridden.

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

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 28 Oct 2026, 19:29 UTC

WeaknessesCWE-770

Technical details

References

Community reviews

Related threats