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CVE-2026-81820

Flowintel HTML Injection in MISP Case History Timeline via Crafted Object Attributes

5.1 Medium

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as:

object UUID;

object name;

attribute value;

attribute type;

comment;

first/last seen values;

IDS flag.

Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through.

The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element.

Version impacted =>3.3.0

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Passive

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

0.39%Up 0.1 points since Aug 28, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.1

Flowintel HTML Injection in MISP Case History Timeline via Crafted Object Attributes

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as:

object UUID;

object name;

attribute value;

attribute type;

comment;

first/last seen values;

IDS flag.

Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through.

The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element.

Version impacted =>3.3.0

Record
CVE-2026-81820
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-79
Updated
2026-11-02
EUVDEUVD-2026-67131 5.1

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as:

object UUID;

object name;

attribute value;

attribute type;

comment;

first/last seen values;

IDS flag.

Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through.

The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element.

Version impacted =>3.3.0

Record
EUVD-2026-67131
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-cv7j-9q69-fxh4 5.1

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object...

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as:

object UUID;

object name;

attribute value;

attribute type;

comment;

first/last seen values;

IDS flag.

Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through.

The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element.

Version impacted =>3.3.0

Record
GHSA-cv7j-9q69-fxh4
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-79
Updated
2026-11-02
NVD 5.1

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as:

object UUID;

object name;

attribute value;

attribute type;

comment;

first/last seen values;

IDS flag.

Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through.

The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element.

Version impacted =>3.3.0

Record
CVE-2026-81820
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-79
Updated
2026-11-02
OSV 5.1

Flowintel HTML Injection in MISP Case History Timeline via Crafted Object Attributes

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as:

object UUID;

object name;

attribute value;

attribute type;

comment;

first/last seen values;

IDS flag.

Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through.

The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element.

Version impacted =>3.3.0

Record
CVE-2026-81820
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-79
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-81820 is a medium vulnerability (CVSS 5.1) in Flowintel, published August 27, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.39%, the 33rd percentile. No source names a fixed version.

References

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