Cyber Resilience

CVE-2026-55841

Published
28 August 2026
Modified
28 August 2026
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS Score 0.0036 28th percentile
Risk Priority 57 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-55841 is a high-severity Improper Neutralization of Special Elements (CWE-138) vulnerability. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 28th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Graylog is a free and open log management platform. Prior to Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3, the FortiGate key-value syslog parser in graylog2-server/src/main/java/org/graylog2/inputs/codecs/GLFortiGateSyslogEvent.java and graylog2-server/src/main/java/org/graylog2/inputs/codecs/SyslogCodec.java mishandles field-like text inside quoted values. GLFortiGateSyslogEvent.getFields() uses…

more

KV_PATTERN and QUOTED_KV_PATTERN, while SyslogCodec.parse() invokes the FortiGateSyslogEvent parser; crafted values containing = or backslash-escaped quotes can cause embedded keys such as srcip, dstip, date, time, and tz to remove or overwrite original top-level fields or produce an invalid message that Graylog discards. An unauthenticated network sender who can submit syslog messages can therefore manipulate security-log fields or evade logging to obscure malicious activity. This issue is fixed in Graylog Server versions 6.3.12, 7.0.7, and 7.1.2 and Graylog Forwarder version 7.3.

CWE(s)
CWE-138

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
attack.mitre.org →
T1059.003 Windows Command Shell Execution
Adversaries may abuse the Windows command shell for execution.
attack.mitre.org →
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
attack.mitre.org →
T1505 Server Software Component Persistence
Adversaries may abuse legitimate extensible development features of servers to establish persistent access to systems.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-48939Shared CWE-138
CVE-2023-42117Shared CWE-138
CVE-2024-38133Shared CWE-138
CVE-2026-20009Shared CWE-138
CVE-2026-32178Shared CWE-138
CVE-2026-26129Shared CWE-138
CVE-2024-51500Shared CWE-138
CVE-2023-7012Shared CWE-138
CVE-2025-5878Shared CWE-138
CVE-2023-22288Shared CWE-138

Affected Assets

—
Graylog Server
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.3.12

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

Input validation enforces neutralization or rejection of special syntactic elements before they reach a downstream interpreter.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles include requirements for safe input handling and neutralization of control characters.

SI-15 Information Output Filtering partial match

Output filtering can neutralize special elements before they are interpreted by a receiving component.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require proper neutralization of inputs to prevent injection flaws.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect instances of CWE-138 but does not itself implement the neutralization controls.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and sanitization that directly prevents improper neutralization of special elements.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for controls against injection and malformed input that cause CWE-138.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture principles reduce attack surface but do not prescribe the specific neutralization techniques needed for CWE-138.

A.8.28 Secure coding partial match
prevents

Secure coding standards require proper escaping and neutralization of special elements, directly eliminating CWE-138.

References