Skip to content
Fencer Intel
low —

CVE-2026-103866 json

Apache Sling Engine: Hand-rolled parameter parser diverges from RFC/container parsing, enabling smuggling

published 4d ago modified 4d ago also EUVD-2026-117433

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

Inconsistent interpretation of HTTP requests ('HTTP Request/Response smuggling') vulnerability in Apache Sling Engine. The engine's query/form parser accepts non-standard percent-escapes, wrong charsets, and continues request processing on such errors.

This issue affects Apache Sling Engine: before 3.0.4.

Users are recommended to upgrade to version 3.0.4, which fixes the issue.

Patch / fix

  • Apache Software Foundation Apache Sling Engine 3.0.4

Is CVE-2026-103866 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-103866 updated cvss 3.7

org.apache.sling/org.apache.sling.engine: Apache Sling Engine: HTTP request smuggling via malformed query and form parsing

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-09).

Affected products

  • Apache Software Foundation Apache Sling Engine

Classification

Weakness
  • CWE-436 Interpretation Conflict
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.