HighCVE-2026-55841

    Graylog2-server: Improper Neutralization of Special Elements (CVE-2026-55841)

    Published Sources: CVE.org, OSV, Hersteller, BSI

    What is affected, what to do

    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.

    Update Graylog2-server to version 6.3.12.

    Affected
    • Graylog2-server gte 7.0.0-alpha.1, < 7.0.7..*
    • Graylog2-server lt *..6.3.12
    Fixed in
    • Graylog2-server 6.3.12

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    7.5

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org, OSV, Hersteller, BSI

    0.6 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 49.4

    Show all metrics
    Severity
    High
    Priority score

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    83.04
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.5
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.5
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.6 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    49.4
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-138

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    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 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.

    Source: NVD (NIST), CVE.org (MITRE), OSV (Open Source Vulnerabilities), cvelistv5, GitHub Security Advisories, BSI CSAF, BSI WID Portal

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    VendorProductAffected versionsFixed in
    Graylog2graylog2-server
    • ≥ 7.0.0-alpha.1, < 7.0.7
    • < 6.3.12
    • —
    • 6.3.12
    Open SourceGraylog
    • < 6.3.12
    • < 7.0.7
    • < 7.1.2
    • 6.3.12
    • 7.0.7
    • 7.1.2
    mavenorg.graylog2:graylog2-server
    • 0.20.0-rc.1-1
    • 0.21.0-beta2
    • 0.21.0-beta3
    • 0.21.0-beta4
    • 0.21.0-rc.1
    • 0.90.0
    • 0.90.1
    • 0.90.3
    • 0.91.0-rc.1
    • 0.91.1
    • 0.91.3
    • 0.92.0
    • 0.92.0-beta.1
    • 0.92.0-rc.1
    • 0.92.1
    • 0.92.1-rc.1
    • 0.92.2
    • 0.92.3
    • 0.92.4
    • 1.0.0
    • 1.0.0-beta.1
    • 1.0.0-beta.2
    • 1.0.0-beta.3
    • 1.0.0-rc.1
    • 1.0.0-rc.2
    • 1.0.0-rc.3
    • 1.0.0-rc.4
    • 1.0.1
    • 1.0.2
    • 1.1.0
    • 1.1.0-beta.1
    • 1.1.0-beta.2
    • 1.1.0-beta.3
    • 1.1.0-rc.1
    • 1.1.0-rc.2
    • 1.1.0-rc.3
    • 1.1.1
    • 1.1.2
    • 1.1.3
    • 1.1.4
    • 1.1.5
    • 1.1.6
    • 1.2.0
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    Weakness classes (CWE)

    • CWE-138Improper Neutralization of Special Elements

      Class

      The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as control elements or syntactic markers when they are sent to a downstream component.

      Entry at MITRE CWE-138

    References & sources

    • github.comGraylog2/graylog2-server/security/advisories/GHSA-gqr6-r77p-c2pjx_refsource_CONFIRM
    • github.comGraylog2/graylog2-server/pull/26050x_refsource_MISC
    • github.comGraylog2/graylog2-server/pull/26056x_refsource_MISC
    • github.comGraylog2/graylog2-server/pull/26057x_refsource_MISC
    • github.comGraylog2/graylog2-server/pull/26059x_refsource_MISC
    • github.comGraylog2/graylog2-server/commit/793df6e8202ea55c15a762e47a2a8a7…x_refsource_MISC
    • github.comGraylog2/graylog2-server/commit/85dc699d6319aea433583dc239077a3…x_refsource_MISC
    • github.comGraylog2/graylog2-server/commit/d5051e604c962ef3d4e5e8e434d0ff4…x_refsource_MISC
    • github.comGraylog2/graylog2-server/commit/dde76d7432c469887d9a95c208083c5…x_refsource_MISC
    • github.comGraylog2/graylog2-serverpackage