CVE-2026-66882Public exploitNetwork attack vector

Browser script execution via unescaped token interpolation

Published Aug 25, 2026 · Updated Aug 25, 2026

XSS in Alembic AshAuthentication 4.8.0 through 4.14.1 and 5.0.0-rc.0 through 5.0.0-rc.12 allows remote attackers to run script via crafted links. The confirmation and magic-link accept templates interpolate unvalidated request parameters into hidden input value attributes through bare EEx expressions that do not escape HTML. Exploitation requires require_interaction? to be enabled and a victim to load a crafted GET link; script then runs in the embedding application's origin, with access bounded by cookie flags and CSP.

CVSS severity2.1
Low
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XSS in Alembic AshAuthentication 4.8.0 through 4.14.1 and 5.0.0-rc.0 through 5.0.0-rc.12 allows remote attackers to run script via crafted links. The confirmation and magic-link accept templates interpolate unvalidated request parameters into hidden input value attributes through bare EEx expressions that do not escape HTML. Exploitation requires require_interaction? to be enabled and a victim to load a crafted GET link; script then runs in the embedding application's origin, with access bounded by cookie flags and CSP.

The record

CVE
CVE-2026-66882
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
Alembic
Product
Ash Authentication
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.8.0 <4.14.2
  2. Affected versionversion=5.0.0-rc.0 <5.0.0-rc.13
  3. Affected versionversion=fe0b4558dbe852fee5d81a460a8355577618a8c8 <* changes=[{"at":"62719710790a150a9eacab9c0a066e0d122d15be","status":"unaffected"},{"at":"0bd5199db066be22b2ca1ec8bc6109e5d62e6070","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Alembic · Ash Authenticationversion=4.8.0 <4.14.2; version=5.0.0-rc.0 <5.0.0-rc.13; version=fe0b4558dbe852fee5d81a460a8355577618a8c8 <* changes=[{"at":"62719710790a150a9eacab9c0a066e0d122d15be","status":"unaffected"},{"at":"0bd5199db066be22b2ca1ec8bc6109e5d62e6070","status":"unaffected"}]

Published CVSS scores

2.1GitHub Security AdvisoryCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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