Threats / Atlassian / CVE-2021-26086
CVE-2021-26086
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Atlassian Jira Server and Data Center vulnerability
Atlassian Jira Server and Data Center contain a path traversal vulnerability allowing remote attackers to read files in the /WEB-INF/web.xml endpoint, exposing sensitive configuration data.
Verdict
Today item — known-exploited.
A path traversal flaw in Jira Server and Data Center permits unauthenticated remote file access. The high EPSS score and active exploitation indicate immediate risk to exposed instances. Patching is critical.
CISA KEV Yes · 2024-11-124EPSS 0.99999 (verify live)5CVSS 5.3 (CISA)3CISA SSVC Exploitation: active · Automatable: yes · Impact: partial3Exploit Public PoC / detection · nuclei template12
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
447 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2024-11-12).
Probability (EPSS)
EPSS 0.99999 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) · Affected: Atlassian, Jira Server and Data Center. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-22 Path Traversal — weakness family: Path traversal / file.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: partialCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 1184 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious request using path traversal sequences to bypass directory restrictions and access the /WEB-INF/web.xml file.
Business
Sensitive application configuration, database credentials, and internal system details are exposed to the attacker.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I extract credentials and system information from the exposed configuration files to plan further attacks.
Business
Attackers gain intelligence for lateral movement, privilege escalation, or attacks against downstream systems.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by atlassianCNA
Credited with finding itNo finder is named in the public CVE record or the scanned vendor advisory — attribution scoped to the sources checked.
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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