Cisco Secure Email Gateway: SQL injection during email parsing (CVE-2026-76461)

A crafted email can inject SQL into affected Cisco AsyncOS Secure Email Gateway processing and lead to root command execution. Upgrade the gateway to remove the vulnerable email parsing path.

Public CVE record · Vendor or publisher advisory · Native module source

CVE advisory record · Vendor advisory · Module source

Result. The marked request reached the backend in the baseline and raised its counter. The native rule refused that request with HTTP 403 and preserved HTTP 200 for the benign probe. The synthetic fixture ran through Eden 1.103.0 on November 12, 2026 (UTC).

The vulnerability

Cisco traces the vulnerability to AsyncOS email parsing. Crafted content delivered as an email can enter a SQL operation and, on affected systems, result in operating-system command execution with root privileges. The delivery mechanism is the processing of a message by the gateway.

Cisco lists patched AsyncOS builds by release train, including 15.5.5-014, 16.0.4-302, and 16.5.0-780. The CVE record reports a CVSS base score of 9.8.

The Eden patch

Tier 1 — declarative policy. The recorded policy denies requests to /api/emails and its descendants. The empty method list leaves the deny unrestricted by HTTP method. This is a coarse rule and blocked the benign probe on the same path.

{
  "version": 1,
  "profile": "http-structure-v1",
  "policy": {
    "version": 1,
    "rules": [
      {
        "scope": {
          "methods": [],
          "path": "/api/emails",
          "descendants": true
        },
        "require": {
          "kind": "deny"
        }
      }
    ]
  }
}

Tier 2 — native Rust module. gabriel_ciscoemailsqli_v1 waits for the request to be complete, checks whether the request target starts with /api/emails/search, and looks for any configured marker in the body. The substring comparison is ASCII case-insensitive. Outside that prefix or without a marker, the module returns Continue. The shown lines are excerpts from the linked source.

const ROUTE: &[u8] = b"/api/emails/search";
static NEEDLES: [&[u8]; 3] = [b"' OR ", b"union select", b"1=1"];

NEEDLES.iter().any(|n| find_ignore_case(body, n).is_some()) && return Ok(Decision::Refuse);

Implement the remediation

Use this procedure in an isolated fixture to reproduce the scoped restriction. Follow the vendor update for the underlying exposure. See deployment prerequisites.

1. Prepare the target. Verify the loaded product and version against the advisory. Use a compatible Eden HTTP interlay and an authenticated operator with Configure permission. Use the recorded declaration and the linked source when applicable.
2. Apply the declarative policy. Scope the policy to /api/emails and descendants (all methods, deny). Set INTERLAY to the target interlay UUID in the authenticated Eden CLI. Run an authenticated GET /api/v1/interlays/{interlay} with X-Eden-Verbose: true. Save its complete current settings object as current-settings.json and retain the prior remediation declaration for recovery. Set IDEMPOTENCY_KEY to a fresh key for this intended mutation.

Save the JSON in the patch section as remediation.json.

jq -e --slurpfile policy remediation.json \
  '.remediation = $policy[0] | {settings: .}' current-settings.json \
  > interlay-update.json
eden api request PATCH "/api/v1/interlays/$INTERLAY" \
  --header "Idempotency-Key:$IDEMPOTENCY_KEY" \
  --body-file interlay-update.json --content-type application/json --confirm

3. Verify the serving policy. Read back the interlay.

eden api request GET "/api/v1/interlays/$INTERLAY" \
  --header 'X-Eden-Verbose:true'

Check that remediation_status.state is ready and both desired and effective SHA-256 values match the intended declaration. Replay the benign and marked requests in the recorded comparison on an isolated target. Check the recorded response and backend outcome for each probe. 4. Restore the previous policy. Coordinate the change with any other operator updating this interlay. Read current settings again and merge the saved remediation field into them. If the prior settings had no remediation field, omit it in the replacement. Send the same PATCH with a fresh idempotency key, then read back the intended state. Repeat the verification probes. Keep the affected route isolated if restoring the prior settings reopens exposure.

Vendor update. Use the advisory to select the fixed release for the installed branch. Reported fixed releases include 15.5.5-014, 16.0.4-302, 16.5.0-780. Follow the vendor’s update instructions and confirm the version actually loaded by the service.

Fixture and probes

The fixture was a synthetic HTTP handler behind Eden. It answered the probes and kept a separate counter that increased when the handler recognized its marker bytes. The counter measures a fixture effect. An HTTP 200 from the baseline does not by itself establish that the counter moved.

Request. POST /api/emails/search for the benign probe and the marked probe.

The fixture sent an ordinary sender search and a SQL predicate in the query field of a synthetic HTTP search. The unfiltered handler recorded the marked HTTP body.

Measured comparison (2026-11-12 UTC)

The values after each status are the observed increases in the backend marker counter.

Signed module authority

The module import returned HTTP 201 and required explicit activation. Signature verification was deferred at import. Read-only inspection returned HTTP 403, admission with a tampered statement returned HTTP 400, and admission with an invalid signature returned HTTP 403. The activation receipt reported the module serving on all expected shards.

After revocation, the same marked request received HTTP 503. Re-approval and reactivation restored HTTP 403. The source digest below identifies the linked Rust file. The binary digest identifies the artifact recorded in the activation evidence.

• Source SHA-256 a54f59724a12c1751d1bb41913d5475e8119d23d659b2e1a88948a195d68f140
• Tested binary SHA-256 36aabeee1d29b55314892c215c7f5d6bb7fd8ba6ea3141fa73a7f02879c27185

Test scope

The report demonstrates an HTTP request filter on a synthetic search route. Cisco's advisory describes crafted email delivery and parsing, which remain outside this module's tested scope. In particular, an SMTP message does not pass through this HTTP body matcher.

Performance

The public evidence for this case does not include request-latency measurements.

Evidence and artifacts

• Public CVE record
• Vendor or publisher advisory
• Published module source