CVE-2026-43968Network attack vector

SSE event injection via incomplete line-separator handling

Published May 11, 2026 · Updated May 11, 2026

CRLF injection in Nine Nines Cowlib 2.6.0 through 2.16.0 allows remote attackers to forge SSE events via crafted field values. cow_sse:event/1 rejects LF but not bare CR in id and event values, while prefix_lines/2 splits data and comments only on LF. An application must pass attacker-controlled fields into SSE generation; compliant clients can then parse injected lines as a new event and dispatch attacker-selected event types and data.

CVSS severity6.3
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

CRLF injection in Nine Nines Cowlib 2.6.0 through 2.16.0 allows remote attackers to forge SSE events via crafted field values. cow_sse:event/1 rejects LF but not bare CR in id and event values, while prefix_lines/2 splits data and comments only on LF. An application must pass attacker-controlled fields into SSE generation; compliant clients can then parse injected lines as a new event and dispatch attacker-selected event types and data.

The record

CVE
CVE-2026-43968
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Nine Nines
Product
Cowlib
Classifications
CWE-93, CAPEC-34, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.0
  2. Affected versionversion=93b2b897cde238506c803faad4d1602d79dba7c9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nine Nines · Cowlibversion=2.6.0; version=93b2b897cde238506c803faad4d1602d79dba7c9

Published CVSS scores

6.3Erlang Ecosystem FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N
4.0NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
CAPEC-34HTTP Response Splitting
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo