Description
Three separate mechanisms allowed a web page on an unrelated origin to read responses that Storm's HTTP
components served to an authenticated user.
The Logviewer reflected the request's Origin header back in Access-Control-Allow-Origin while also
sending Access-Control-Allow-Credentials: true. The published security model documents a permissive
Access-Control-Allow-Origin: * posture as accepted, which is safe precisely because browsers refuse to
honour * together with credentials; reflecting the concrete origin removes that protection.
The shared CORS filter used by the UI, the Logviewer and DRPC was configured with a response header name
where an initialisation parameter name was expected. The container ignored the setting and applied its own
defaults, which allow credentials.
Finally, the UI and Logviewer wrapped API responses in a caller-supplied JSONP callback for every GET
request. A script element on any origin can load such a response, which bypasses the same-origin policy
entirely rather than negotiating it, and there was no way to turn the behaviour off.
In each case the effect is that a page visited by an authenticated operator can read cluster, topology and
log data on their behalf.
Mitigation
Upgrade to 3.1.0, where the Logviewer no longer reflects the request origin in a credentialed response, the
CORS filter is configured explicitly, and JSONP wrapping is governed by ui.enable.jsonp, which defaults to
false.
Note that disabling JSONP is a behaviour change for tooling that passes a callback query parameter; such
tooling should be moved to ordinary JSON requests.
Users who cannot upgrade immediately should place the UI, Logviewer and DRPC HTTP endpoints behind a reverse
proxy that strips Access-Control-Allow-Origin and Access-Control-Allow-Credentials from responses and
rejects requests carrying a callback parameter.
Credit
The ASF -- found using Claude agents to study the security of open-source projects, validated and reported by Apache Storm.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.1): severity, escalated by confirmed exploitation. This CVE's 8.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.1 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
The CVE record names the fixed release. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it