VulnerabilityPublished 28 Oct 2026

CVE-2026-116267: MIME-tools (Perl module) · Inefficient Algorithmic Complexity

Affects MIME-tools (Perl module)Source CVE Database V5

Not known to be exploited : upgrade to 5.521 soon.

Data as of 28 Oct 2026, 17:57 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.

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 MIME-tools to version 5.521 or later, where this vulnerability has been fixed. No other mitigations are indicated by the vendor advisory.

Description

MIME::Parser versions before 5.521 for Perl contain an inefficient algorithmic complexity vulnerability that can lead to memory exhaustion. This occurs when deeply nested MIME messages are truncated, causing error messages to be indented and logged at each nesting level, resulting in quadratic growth of stored diagnostics. The default configuration does not limit nesting depth, making the parser susceptible to this issue.

Impact

An attacker can cause the MIME::Parser to consume excessive memory by sending a deeply nested truncated MIME message, potentially leading to denial of service due to memory exhaustion. No public exploits or in-the-wild exploitation are currently known.

Summary

The vulnerability in MIME::Parser (CVE-2026-116267) arises from inefficient handling of deeply nested MIME messages that are truncated without closing boundaries. Each parser diagnostic message is indented by three spaces per nesting level, and when a message nested N levels deep ends prematurely, an error is logged at each level with indentation proportional to its depth. This causes the total size of stored diagnostics to grow approximately with the square of the nesting depth, leading to potential memory exhaustion. Versions prior to 5.521 are affected, with the issue fixed in version 5.521.

CWE-407Inefficient Algorithmic Complexity (opens in a new tab)
Class weaknessLikelihood of exploit: Low
An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

metacpan.org/release/DSKOLL/MIME-tools-5.521/changes (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 28 Oct 2026, 17:46 UTC

WeaknessesCWE-407

Technical details

References

Community reviews

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