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Flowintel EUVDEUVD-2026-67133

| CVE-2026-81827 MEDIUM
Improper Input Validation (CWE-20)
2026-08-27 CIRCL GHSA-3hq8-r684-4qwf
6.9
CVSS 4.0 · Vendor: CIRCL
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Send crafted HTTP POST to login endpoint
  2. Delivery
    Supply email with embedded CR/LF payload
  3. Exploit
    WTForms validator not invoked, validation silently skipped
  4. Execution
    Unsanitized email interpolated into warning and audit log calls
  5. Persist
    CRLF splits log output into multiple physical lines
  6. Impact
    Forged log entries written to security audit trail

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V2 - Validation and Business Logic Input validation, allowlisting
Exploitation Conditions

No special conditions are required beyond network access to the Flowintel login endpoint on a deployment running version 3.3.0 or later. The CVSS vector PR:N confirms no authentication is needed; AC:L and AT:N confirm no race condition or special timing is required. The attacker only needs to submit an HTTP POST with a crafted email parameter - the login itself fails (no application access is gained), but the malformed input is written to logs before rejection. Exploitation is limited to log integrity: the attacker cannot extract data, execute code, or escalate privileges via this path. The primary factor limiting real-world impact is deployment scope - Flowintel installations restricted to internal networks or VPN-gated access have a substantially smaller attacker population than publicly exposed instances.

Impact

The CVSS 4.0 score of 6.9 with vector AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N accurately reflects that this is a network-accessible, zero-prerequisite integrity flaw with no confidentiality or availability impact. Real-world risk is elevated specifically for organizations that treat Flowintel audit logs as a trusted security record: forged entries could obscure actual intrusion attempts, attribute activity to wrong actors, or break SIEM parsers expecting structured single-line records. EPSS data was not provided in the available intelligence, and the vulnerability does not appear in CISA KEV, indicating no confirmed widespread active exploitation. The attack complexity is genuinely low - no authentication, no special configuration, one HTTP request - but the impact domain is narrow. Defenders should weight the risk against their logging pipeline's role in incident response: organizations using Flowintel audit logs as an authoritative source for compliance or forensic purposes face meaningfully higher practical risk than those using them only informally.

Exploit ScenarioDerived

An unauthenticated attacker sends a POST request to the Flowintel login endpoint with an email field value such as attacker@evil.com\r\nINFO 2026-07-23 admin logged in successfully from 10.0.0.1. Because WTForms validation is never actually invoked, the input passes through to the logging layer, where the embedded CRLF causes the single logger.warning() call to produce two physical log lines - the injected second line appearing as a legitimate audit event. A security analyst reviewing post-incident logs would encounter a fabricated entry that could obscure the real attacker's activity or falsely implicate a legitimate user.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 27, 2026

Log injection in Flowintel versions 3.3.0 and later allows unauthenticated remote attackers to forge arbitrary log lines by supplying email values containing CR/LF characters at the login endpoint. The vulnerability traces to a misuse of WTForms validation - the code constructed a validator object via Email(email) without invoking it, leaving attacker-controlled input unsanitized before it was interpolated into both the standard warning logger and the custom audit logger via Python f-strings. No public exploit code has been identified and the vulnerability is not listed in CISA KEV, but the attack is trivially executable with a single HTTP request against any network-exposed deployment, and its impact falls directly on security logging integrity rather than application confidentiality or availability.

RemediationAI

Update Flowintel to the version incorporating commit 660b4cc405055a794f157d3e4612520f12fe85bf (https://github.com/flowintel/flowintel/commit/660b4cc405055a794f157d3e4612520f12fe85bf); a specific tagged release version was not confirmed in the available data, so verify the target release includes this commit before deploying. The patch corrects WTForms validator invocation, replaces f-string log interpolation with parameterized %r formatting, and adds _sanitize_log_fragment() across all log paths in the audit logger. If immediate patching is not feasible, restrict network access to the Flowintel login endpoint to trusted IP ranges - this reduces the attacker population but does not eliminate the flaw for any authenticated or authorized user who submits a crafted email. Additionally, configure any SIEM or log aggregation system ingesting Flowintel output to flag anomalous multi-line log entries or unexpected log record counts from the login path as a detection signal for active exploitation attempts.

Affected VersionsENISA

flowintel 0 ≤3.3.0

Affected Packages

euvd flowintel no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Flowintel is a threat intelligence management platform developed by CIRCL, affected at CPE cpe:2.3:a:flowintel:flowintel:*:*:*:*:*:*:*:* from version 3.3.0 onward. The root cause is CWE-20 (Improper Input Validation) manifesting as a WTForms API misuse: calling Email(email) instantiates a validator object but never runs it - the correct invocation is Email()(form, form.email), which calls the validator against the form field and raises a ValidationError on malformed input. With validation silently skipped, raw email strings containing CR (\r) and LF (\n) characters reached two distinct log sinks: a warning logger using an f-string interpolation pattern, and the custom flowintel_log audit logger. Because neither sink encoded newlines, a single attacker-controlled login attempt could split into multiple physical log records. The patch addresses all three root causes: correct validator invocation, switch to parameterized logging (%r formatting), and introduction of _sanitize_log_fragment() applied uniformly to IP addresses, prefixes, messages, and key-value kwargs in the audit logger.

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Severity by source

Vendor (CIRCL) PRIMARY 6.9 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
vuln.today AI 5.3 MEDIUM

Network-reachable login form requires no authentication; integrity impact is limited to log file manipulation with no scope change beyond the vulnerable system.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (CIRCL).

CVSS VectorVendor: CIRCL

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
Low
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

Affected versions of Flowintel incorrectly attempted to validate login email addresses by calling Email(email). That does not perform WTForms field validation; it merely constructs a validator object.

Consequently, malformed attacker-controlled email input could continue through the login process and be written to security-relevant logs. The vulnerable code inserted the supplied email into both a warning log and the custom audit logger. Since CR/LF characters were not escaped, an unauthenticated attacker could potentially inject additional physical log lines or forge misleading log entries.

The patch corrects the validation call to Email()(form, form.email), changes the standard logging call to parameterized logging, and introduces _sanitize_log_fragment() so carriage returns and line feeds are encoded instead of creating new records.

Version impacted >=3.3.0

Threat Intelligence Overview

EPSS Score
0.3%
Top 78% exploitable
Prevalence
Low
niche threat intelligence platform developed by CIRCL
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

CVE-2026-81826 CRITICAL
9.1 Aug 27

Persistent session hijacking is possible in Flowintel version 3.3.0 and later because the application fails to invalidat

CVE-2026-81662 HIGH
8.6 Aug 27

Remote code execution in Flowintel's alerts settings update endpoint (versions >= 3.3.0) allows an authenticated high-pr

CVE-2026-81818 HIGH
8.6 Aug 27

Privilege escalation in Flowintel's administrative user-edit API allows an organization administrator to modify full adm

CVE-2026-81743 HIGH
7.5 Aug 27

Remote code execution via log path traversal in Flowintel 3.3.0 and later is achievable by an authenticated administrato

CVE-2026-81817 HIGH
7.2 Aug 27

Broken object-level authorization across Flowintel task endpoints allows authenticated editor-level users to perform una

CVE-2026-81659 HIGH
7.1 Aug 27

Flowintel's PDF export pipeline passes attacker-controlled note content to Pandoc with the raw_tex extension enabled, al

CVE-2026-69075 MEDIUM
6.9 Aug 03

Stored XSS via Vue template injection in FlowIntel allows an authenticated low-privilege user to persist malicious Vue i

CVE-2026-9813 MEDIUM
6.2 May 28

Server-side request forgery in FlowIntel up to version 3.3.0 allows a low-privileged authenticated user to coerce the ap

CVE-2026-81819 MEDIUM
5.3 Aug 27

Insufficient authorization on the Flowintel /my_assignment/user API endpoint allows any authenticated API user to retrie

CVE-2026-81753 MEDIUM
5.1 Aug 27

Stored cross-site scripting in Flowintel case notes allows an authenticated low-privileged user to inject malicious Java

CVE-2026-81814 MEDIUM
5.1 Aug 27

Stored cross-site scripting in Flowintel's calendar view (versions >= 3.3.0) allows an authenticated user with case-crea

CVE-2026-81820 MEDIUM
5.1 Aug 27

Stored cross-site scripting in Flowintel's MISP timeline renderer allows an authenticated low-privileged attacker to inj

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