CyberSecBulletin
CVE-2026-39915NVD status: Deferred

TIM Flow: Improper Neutralization of CRLF Sequences in HTTP Headers

Published Updated By the CyberSecBulletin desk

CVE-2026-39915 is a high-severity improper neutralization of CRLF sequences in HTTP headers vulnerability in TIM Flow from Tim-solutions, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 26.0.6 as the first without the flaw, so updating TIM Flow to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update TIM Flow to 26.0.6 or a later version.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  3. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
TIM SolutionsTIM Flowbefore 26.0.626.0.6

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N. Scored by CNA (vulncheck.com).

Scoring systemScoreSeverityScored by
CVSS 4.08.5HighCNA (vulncheck.com)
CVSS 3.18.1HighCNA (vulncheck.com)

Official description

TIM Flow before 26.0.6 contains a CRLF injection vulnerability that allows remote attackers to inject arbitrary HTTP headers and response body content by embedding unsanitized carriage return and line feed sequences in the rt URL parameter, which is reflected into Set-Cookie response headers. Attackers can craft malicious requests to induce authenticated users to execute arbitrary JavaScript in their browser context, enabling session token theft and account credential modification.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of CRLF Sequences in HTTP Headers

The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers.

How developers prevent this class of flaw

  • Construct HTTP headers very carefully, avoiding the use of non-validated input data.
  • Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

More Improper Neutralization of CRLF Sequences in HTTP Headers vulnerabilities (CWE-113)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Neutralization of CRLF Sequences in HTTP Headers vulnerabilities

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