AhsayCBS system password-check bypass (CVE-2026-105133)

Manipulating input to the affected AhsayCBS system-password check can bypass authentication. Update AhsayCBS to protect backup administration from requests that should fail the password check.

Public CVE record · Vendor or publisher advisory · Source and API bundle

cve.now entry.

Eden terminates the HTTP connection to the affected product, evaluates a declarative policy and — in tier 2 — a separately compiled native Rust module under signed module authority, before any byte reaches the application. It does not patch the affected component; the vendor's fixed release remains the durable repair.

Status: live two-tier remediation recorded 2026-11-11 on the installed eden-product-release:1.103.0-single lab container (image sha256:809293e1f0b525ac04698d1fa8d7ffdc66cbee1ff690b082ba26b4d050f08416). Both bypass branches of the fixture's login check are refused (the bypass parameter and the missing-password form); ordinary credential checks pass.

The vulnerability

Improper authentication in the AhsayCBS system password check lets a remote attacker bypass login protections (v7-v10; earlier hotfixes incomplete). KEV-listed.

The Eden patch

Tier 1 — declarative policy (blunt, fail-closed): deny on the affected route family — takes the whole surface offline, legitimate calls included.

Tier 2 — native module: gabriel_ahsayauth_v1, binary SHA-256 53cda7c4ed3e240a17da33acffb9a398242da24e8395ebaa7dff475062e52cb4 (source 0af7371242ff2ffda9edd57c4ba4559a29d07023fd5c2e4232bd52e38d0663c7). See the comparison table for what it keys, and the honest scope for what it cannot.

Implement the remediation

The commands are operator examples for the recorded scope. Compare fixture routes and software selectors with the intended deployment before use. 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. Open the deployment example and API instructions. The bundle identifies module gabriel_ahsayauth_v1 version 1.0.0 and the SDK revision in patch.toml. Run the policy extraction from the adapter directory.
2. Apply the declarative policy. Scope the policy to /cb5/loginModule 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.

jq -e '.tier1' deployment.json > 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. Use the request and expected-status table in the linked API example alongside the observed comparison. 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.

Native module gabriel_ahsayauth_v1

1. Prepare the archive. Use the version 1.0.0 bundle for source, target, and build profile. Configure independent host approval for the installed Eden release. Use the authenticated principals required by the native authority contract. Set PATCH_ARCHIVE to the exact schema-2 package and PACKAGE_SHA256 to its expected archive digest. Verify and import it using the same target interlay.

printf '%s  %s\n' "$PACKAGE_SHA256" "$PATCH_ARCHIVE" | sha256sum --check &&
  eden api request PUT "/api/v1/interlays/$INTERLAY/patch-packages/$PACKAGE_SHA256" \
    --body-file "$PATCH_ARCHIVE" \
    --content-type application/vnd.eden.patch-package.v2+tar --confirm

2. Approve and activate. Enroll the publisher key, attest host software inventory, and inspect the configuration returned by import. Obtain independent host approval. Sign the typed statement with the matching SDK. Send the admit action followed by activate for the prepared operation. Use the applicable typed payload for each action in authority-action.json.

eden api request POST "/api/v1/interlays/$INTERLAY/native-authority" \
  --body-file authority-action.json --content-type application/json --confirm

3. Verify the operation. Read the receipt through the same endpoint. Confirm serving_now and the full expected shard acknowledgment. Repeat the report’s benign and marked probes and check the backend observations.
4. Revoke or restore. Send revoke with the exact operation UUID. Mandatory protection can refuse traffic until a compatible operation is approved and activated. Verify the restored receipt and repeat the probes.

Vendor update. Use the advisory to select the fixed release for the installed branch. Reported fixed releases include 10.3.4.45. Follow the vendor’s update instructions and confirm the version actually loaded by the service.

Measured comparison (live, 2026-11-11)

Performance trace (Eden telemetry, live 2026-11-11)

Measured with Eden's built-in request telemetry (gateway.request.baseline spans, read back through /api/v1/analytics/telemetry?signal=traces), not client wall-clock. Latency Eden introduces per remediation arm for this case:

Eden-added latency for the tier-2 remediation: benign requests complete in 447 µs mean (p50 426 µs, p95 591 µs) in-product, module evaluation included. Honest scope: lab fixtures on one host, fresh connection per measured request, warm requests only; module reactivated shards 2/2 with a fresh signed statement per measurement; spans carry the full authority lineage (module SHA-256, operation, publication). Not the EDEN-3640 performance qualification contract.

Tested against: eden-product-release:1.103.0-single (image sha256:809293e1f0b525ac…, build target eden_service_single, tooling revision 81a0724a…). Raw data: module2/telemetry-ab/ahsayauth-telemetry.json and module2/tier1-ab/ahsayauth-tier1.json.

Authority lifecycle and negatives

Driven through the full signed lifecycle (module2/evidence/ahsayauth-module.json): enroll_key (Ed25519 public key), independent-host inventory, inspect (bindings derived without mapping code), host approve, signed admit (prepared, serving_now: false), activate — receipt serving_now: true, applied_shards == expected_shards (2/2). Negatives held: read-only inspect -> 403, tampered statement binding -> 400, flipped signature bit -> 403. revoke failed the interlay closed (503, nothing forwarded, zero backend effects) and a fresh host approval plus a newly signed activation restored the module's behavior.

Honest scope

The fixture replicates the delivery shape and exploit prerequisite with a harmless marker effect; no real vendor component runs here. The module keys only the primitive listed above — bypass variants (encodings, alternate routes, crafted members other than the one keyed) are not bypass-tested and are out of scope; the rule is a lab-grade partial by construction. The vendor's fixed release remains the durable repair. Perf: request-path A/B not re-run for this batch (see README); activation telemetry measured ~0.14 s one-time load.

Cost record (per-CVE ledger)

$0.0789 USD (marginal session growth: 1,128,044 in + 46 out tokens, 3 turns; shared debug windows overlap).

Evidence appendix

• cve.now entry
• Raw evidence: gabriel-2026-11-11/module2/evidence/ahsayauth-module.json
• Deployment: installed eden-product-release:1.103.0-single lab container (image sha256:809293e1f0b525ac04698d1fa8d7ffdc66cbee1ff690b082ba26b4d050f08416)
• Skill: eden-vulnerability-remediation

Decision flow

This is the available form-byte predicate. It neither verifies a password nor establishes coverage of every Ahsay login path.

Complete native module source

The complete available source for gabriel_ahsayauth_v1 is reproduced below from the reviewed repository snapshot. The source SHA-256 is 0af7371242ff2ffda9edd57c4ba4559a29d07023fd5c2e4232bd52e38d0663c7. This identifies the source bytes, rather than independently proving the binary build or the recorded test results. The case’s experiment status and limitations still apply, including any failed import, partial coverage, or withdrawn claim. Original source comments are preserved verbatim.

//! Gabriel module: refuse the system-password-check bypass parameter (CVE-2026-105133 shape)
//!
//! CVE-2026-105133: improper authentication in the AhsayCBS system
//! password check lets a remote attacker bypass login protections.
//! This module refuses login bodies carrying the bypass primitive;
//! ordinary credential checks pass unchanged. no_std; no allocator, storage, background work or state.

#![no_std]

use core::mem::size_of;
use core::panic::PanicInfo;
use eden_gateway_remediation::message::{Availability, MessageInput};
use eden_gateway_remediation::module::{
    ApiHeader, CONTINUE, Decision, EDIT, EditSink, Edits, Failure, ModuleOutput, NEED_MORE, REFUSE, RemediationModule,
};
use eden_gateway_remediation::native_http_v3::{self as http, Api, Input, Request};

/// Route prefix in scope.
const ROUTE: &[u8] = b"/cb5/loginModule";

/// The byte primitives this module refuses on that route.
static NEEDLES: [&[u8]; 1] = [b"sys_pwd_bypass"];

fn find(haystack: &[u8], needle: &[u8]) -> Option<usize> {
    if haystack.len() < needle.len() || needle.is_empty() {
        return None;
    }
    let mut i = 0usize;
    while i + needle.len() <= haystack.len() {
        let mut j = 0usize;
        let mut same = true;
        while j < needle.len() {
            if haystack[i + j] != needle[j] {
                same = false;
                break;
            }
            j += 1;
        }
        if same {
            return Some(i);
        }
        i += 1;
    }
    None
}

struct gabriel_ahsayauth_v1;

impl RemediationModule<Request<'_>> for gabriel_ahsayauth_v1 {
    fn evaluate(&self, request: &Request<'_>, edits: &mut Edits<'_>) -> Result<Decision, Failure> {
        let _ = edits;
        let _ = match request.header_count() {
            Availability::Ready(count) => count,
            Availability::NeedMore => return Ok(Decision::NeedMore),
            Availability::Unavailable => return Err(Failure),
        };
        let message = request.message();
        let head = message.prefix();
        let line_end = head.iter().position(|&b| b == b'\r').unwrap_or(head.len());
        let request_line = &head[..line_end];
        let path_at = request_line.iter().position(|&b| b == b' ').unwrap_or(request_line.len());
        let target = &request_line[path_at + 1..];
        if !target.starts_with(ROUTE) {
            return Ok(Decision::Continue);
        }
        if !message.is_complete() {
            return Ok(Decision::NeedMore);
        }
        let body_range = match request.body_range() {
            Availability::Ready(range) => range,
            Availability::NeedMore => return Ok(Decision::NeedMore),
            Availability::Unavailable => return Err(Failure),
        };
        let body = match message.bytes(body_range)? {
            Availability::Ready(bytes) => bytes,
            Availability::NeedMore => return Ok(Decision::NeedMore),
            Availability::Unavailable => return Err(Failure),
        };
        if NEEDLES.iter().any(|n| find(body, n).is_some()) {
            return Ok(Decision::Refuse);
        }
        // The lab fixture models a second bypass branch: a system-user login
        // form that omits the password field entirely. Presence of `sys_user=`
        // without `sys_password=` is refused for the same reason as the
        // marker form: the vulnerable check must not decide on markers.
        if find(body, b"sys_user=").is_some() && find(body, b"sys_password=").is_none() {
            return Ok(Decision::Refuse);
        }
        Ok(Decision::Continue)
    }
}

static API: Api = Api {
    header: ApiHeader { version: http::VERSION, table_size: size_of::<Api>() as u32 },
    input_size: size_of::<Input>() as u32,
    output_size: size_of::<ModuleOutput>() as u32,
    sink_size: size_of::<EditSink>() as u32,
    message_size: size_of::<MessageInput>() as u32,
    state_bytes: 0,
    capabilities: CONTINUE | REFUSE | NEED_MORE | EDIT,
    required_inputs: 0,
    evaluate: Some(evaluate),
};

unsafe extern "C" fn evaluate(input: *const Input, sink: *const EditSink, output: *mut ModuleOutput) -> i32 {
    unsafe { http::invoke(&gabriel_ahsayauth_v1, input, sink, output) }
}

#[unsafe(no_mangle)]
pub extern "C" fn eden_http_remediation_v3() -> *const Api {
    &API
}

#[panic_handler]
fn panic(_information: &PanicInfo<'_>) -> ! {
    loop {
        core::hint::spin_loop();
    }
}