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Full vulnerability report · 2021
CVE-2021-26084High confidence

Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection Vulnerability

Atlassian · Confluence Server and Data Center

9.8CriticalCVSS 3.1
Recommended action
Patch now

CISA confirms exploitation in the wild and lists 2021-11-17 as the remediation due date.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • CISA confirms exploitation in the wild.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 100.00% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Atlassian Confluence Server and Data Center and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-12905

CISA KEV mirrored by ENISA

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated attacker to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0 before 7.12.5.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 3 Nov 2021. Evidence sources: cisa_kev.
ENISA score
9.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch now

CISA confirms exploitation in the wild and lists 2021-11-17 as the remediation due date.

Patch available
01

What, why and how

Atlassian Confluence Server and Data Server contain an Object-Graph Navigation Language (OGNL) injection vulnerability that may allow an unauthenticated attacker to execute code.

What

Atlassian Confluence Server and Data Server contain an Object-Graph Navigation Language (OGNL) injection vulnerability that may allow an unauthenticated attacker to execute code.

Why

The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

What

Atlassian Confluence Server and Data Server contain an Object-Graph Navigation Language (OGNL) injection vulnerability that may allow an unauthenticated attacker to execute code.

Why

The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2021-11-03. Known ransomware campaign use is recorded.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection') → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-917 ↗

CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection'). The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkUnauthenticatedRemote code executionCWE-917CISA KEVPublic exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2021-12905Known-exploited evidence recorded

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated attacker to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0 before 7.12.5.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210901Security Bulletin 01 Sep 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 01 Sep 2021, published on 1 September 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-677Multiples vulnérabilités dans Atlassian Confluence Server et Data Center

De multiples vulnérabilités ont été découvertes dans Atlassian Confluence Server et Data Center. Elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance et une atteinte à la confidentialité des données. La vulnérabilité CVE-2021-26084 est activement exploitée. De plus, des codes d'exploitation sont disponibles publiquement sur Internet.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-011176Confluence Server および Data Center におけるインジェクションに関する脆弱性

Confluence Server および Data Center には、インジェクションに関する脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5873최근 해킹 공격에 활용되는 취약점 보안 업데이트 권고

우회 취약점(CVE-2021-45232)[1] ㅇ Apache HTTP Server에서 경로 탐색(Path Traversal)으로 인해 발생하는 정보노출 취약점(CVE-2021-42013)[2] ㅇ Apache HTTP Server에서 경로 탐색(Path Traversal)으로 인해 발생하는 정보노출 취약점(CVE-2021-41773)[3] ㅇ Apache OFBiz에서 발생하는 크로스 사이트 스크립팅(XSS) 취약점(CVE-2020-9496)[4] ㅇ Apache OFBiz에서 발생하는 역직렬화 취약점(CVE-2021-26295)[5] ㅇ Apache Struts에서 발생하는 원격코드 실행 취약점(CVE-2020-17530)[6] ㅇ Apache Struts에서 사용자 입력값 검증 미흡으로 발생하는 원격 코드 실행 취약점(CVE-2021-31805)[7] ㅇ Apache Tomcat이 AJP request 메시지를 처리할 때, 메시지에 대한 처리가 미흡하여 발생하는 원격코드실행 취약점(CVE-2020-1938)[8] ㅇ Apache Log4j에서 발생하는 원격코드 실행 취약점(CVE-2021-44228)[9] ㅇ Atlassian Confluence Server 및 Data Center에서 OGNL 인젝션으로 인해 발생하는 원격코드실행 취약점(CVE-2021-26084)[10] ㅇ BIG-IP에서 iControl REST 인증 미흡으로 인해 발생하는 불충분한 인가 취약점(CVE-2022-1388)[11] ㅇ BIG-IP, BIG-IQ의 iControl REST 인터페이스에서 발생하는 원격 코드 실행 취약점(CVE-2021-22986)[12] ㅇ Grafana 소프트웨어에서 경로탐색(Directory Traversal)으로 인해 발생하는 정보노출 취약점(CVE-2021-43798)[13] ㅇ Inspur ClusterEngine V4.0에서 발생하는 원격 코드 실행 취약점(CVE-2020-21224)[14] ㅇ Oracle WebLogic Server에서 발생하는 원격 코드 실행 취약점(CVE-2021-2109)[15] ㅇ SMBv3 프로토콜이 조작된 패킷을 처리할 때 버퍼오버플로우로 인해 발생하는 원격코드실행 취약점(CVE-2020-0796)[16] ㅇ Spring Cloud Gateway에서 발생하는 원격코드 실행 취약점(CVE-2022-22947)[17] ㅇ Spring Core에서 발생하는 원격코드실행 취약점(CVE-2022-22965)[18] ㅇ Spring Cloud Function에서 발생하는 원격코드실행 취약점(CVE-2022-22963)[18] ㅇ VMware vCenter Server 원격 코

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5392추석 연휴기간 사이버 공격 대비 보안 권고 사항 (상세)

안 권고 사항 o 서버 보안 강화 방안 ① 보안 지원이 종료된 운영체제 및 소프트웨어는 신속하게 업그레이드를 수행하고, 매월 운영체제 및 주요 프로그램(메일, 웹, JAVA 등)의 보안 업데이트 확인적용 ② 기본 원격포트(22. 3389) 사용을 자제하고, OTP 등을 통한 추가 인증 강화 ③ VPN 장비를 운영하는 경우, 허가된 사용자와 단말기만 업무망에 접근할 수 있도록 설정하고 OTP 등을 통한 추가 인증 강화 ④ 다수의 서버를 운영하는 경우 내부 서버 간 원격접속이 불가능 하도록 접근 제어 설정 ⑤ AD 인프라를 운영 중인 기업의 경우, 관리자 그룹 계정의 최소화 및 관련 PC의 인터넷망 분리 운영 ⑥ 주요 관리자 PC에 대한 주기적인 보안 점검 및 인터넷망 분리 운영 ☞ 특히 아래의 취약점을 이용하여 해킹사고가 발생 할 수 있으니 반드시 보안 업데이트 등 조치 필요 (1) MS 윈도우 Exchange 서버 취약점 보안 업데이트 권고 (CVE-2021-26855, 26857, 27065, 26585, 27065, 31207, 34473, 34523) [6] (2) MS 윈도우 프린터 스풀러 취약점 보안 업데이트 권고 (CVE-2021-34481, 34527, 1657) [7] (3) 아틀라시안 컨플루언스 제품 취약점 보안 업데이트 권고 (CVE-2021-26084) [8] o PC 보안 강화 방안 ① 피싱 메일에 주의하고 본문 링크 클릭, 첨부파일 다운로드, 실행에 주의 ② 매월 운영체제 및 주요 프로그램(웹브라우저, Flash, Java 등)의 보안 업데이트 확인 적용 ③ 상용 메일을 통한 주요 업무 자료 송수신 금지 ※ 불가피한 경우, OTP 설정 및 허가된 사용자 단말기 추가 등을 통해 인증 강화 ☞ 특히 아래의 취약점을 이용하여 감염되는 사례가 발생할 수 있으니 임시 대응 방안 조치 필요 (1) MS MSHTML 취약점 주의 권고 (CVE-2021-40444) [9] ※ `21.9.14 현재 자동 보안패치없음 o NAS 보안 강화 방안 ① 최초 설치 시 기본 관리자 패스워드는 반드시 변경 후 사용 ② 자동 업데이트를 활성화하여 최신 펌웨어 유지 ③ 인터넷을 통한 직접 접속은 차단하고, 사내망에서 운영 권고 ※ 불가피한 경우, 장비의 비밀번호 관리 및 백업, 보안 업데이트 등 철저한 관리 필요 ☞ 특히 아래의 취약점을 이용하여 감염되는 사례가 있으니 반드시 보안 업데이트 등 조치 필요 (1) QNAP社 NAS 제품 보안 업데이트 권고 (CVE-2021-28799) [10] o 공통 보안 강화 방안 ① 사용하지 않는 시스템은 전원을 종료하여 해킹 경로로 활용되는 것을 사전 방지 ② 중요 파일 및 문서

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5383Atlassian Confluence 제품 취약점 보안 업데이트 권고

Confluence Server 및 Data Center에서 OGNL 인젝션으로 인해 발생하는 원격코드실행 취약점(CVE-2021-26084) [1]

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 30 Aug 2021 · Last source change 16 Dec 2025, 18:04 UTC · CWE-917 · Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')

CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-12905
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCISA ADP
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    unspecified < 6.13.23; 6.14.0 < unspecified; unspecified < 7.4.11; 7.5.0 < unspecified; unspecified < 7.11.6; 7.12.0 < unspecified; unspecified < 7.12.5 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    Confluence Server: unspecified < 6.13.23, 6.14.0 < unspecified, unspecified < 7.4.11, 7.5.0 < unspecified, unspecified < 7.11.6, 7.12.0 < unspecified, unspecified < 7.12.5; Confluence Data Center: unspecified < 6.13.23, 6.14.0 < unspecified, unspecified < 7.4.11, 7.5.0 < unspecified, unspecified < 7.11.6, 7.12.0 < unspecified, unspecified < 7.12.5 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-12905↗CISA KEV record↗CVE authority or vendor reference↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-26084 · cve.blacktree.nl