How to Fix CVE-2026-35574: CRM (Bundle Sibling)

By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor

Last verified: 2026-05-25

CVE-2026-35574 is a sibling vulnerability in the same Churchcrm CRM advisory bundle as CVE-2026-35534. The same patched build closes every CVE in the bundle, so the remediation procedure for CVE-2026-35574 matches the primary write-up.

What is different about CVE-2026-35574?

ChurchCRM is an open-source church management system. Prior to 6.5.3, a stored Cross-Site Scripting (XSS) vulnerability in ChurchCRM's Note Editor allows authenticated users with note-adding permissions to execute arbitrary JavaScript code in the context of other users' browsers, including administrators. This can lead to session hijacking, privilege escalation, and unauthorized access to sensitive church member data.

Impact is consistent with the bundle: elevation of privilege to administrator or root on the affected host. The patched build closes every code path in the advisory in one update.

Resolve

Apply the patched build per the primary write-up: How to Fix CVE-2026-35534.

For a quick check, confirm the running version of CRM:

# Confirm the installed version via your package manager
dpkg -l | grep -i crm   # Debian/Ubuntu
rpm -qa | grep -i crm   # RHEL/CentOS/Rocky

Frequently asked questions

Is CVE-2026-35574 being actively exploited?

Not at the time of writing. It is not listed in CISA's Known Exploited Vulnerabilities catalog. That status can change, so monitor the vendor advisory and the KEV catalog if the system is exposed.

How severe is CVE-2026-35574?

CVSS rates it 7.3 (High). Use that score to set your patch priority alongside the other items in your queue.

Do I have to take CRM offline to apply the patch?

It depends on the deployment. High-availability or clustered installs can usually patch one node at a time with no full outage. Standalone installs typically need a short restart. Always follow the vendor's documented upgrade steps.

What if my vulnerability scanner still flags CVE-2026-35574 after I patch?

Re-run the scan after a service restart, then confirm the scanner's plugin set is up to date. Some scanners detect by banner version only and lag the official fix metadata by a release.

Related fixes

Related guides worth a look while you sort this one out:

• How to Fix CVE-2026-35569: Cross-site scripting in apostrophe
• How to Fix CVE-2026-3557: CWE-122: Heap-based Buffer Overflow in Hue Bridge
• How to Fix CVE-2026-35570: Path traversal in openclaude
• How to Fix CVE-2026-35571: Emissary has Stored XSS via Navigation Template Link Injection
• How to Fix CVE-2026-35572: CRM (Bundle Sibling)
• How to Fix CVE-2026-35573: CRM (Bundle Sibling)

References

• Official vendor advisory: https://github.com/ChurchCRM/CRM/security/advisories/GHSA-cx82-8xrh-7f5c
• NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-35574
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Primary write-up: How to Fix CVE-2026-35534

Written by Sai Kiran Pandrala

Identify

When this symptom shows up on this unit, three patterns repeat:

1. Recent firmware update changed behavior. the symptom started within a week of an OTA push. Rollback or wait for the hotfix. 2. Environmental trigger, temperature, humidity, line voltage, network changes. Look at what changed in the environment. 3. Cumulative wear: components like batteries, gaskets, fans degrade over time. Replace the consumable rather than chasing a software fix.

Knowing which pattern applies saves time on the wrong fix.

Safety + preconditions

Before any work on this device:

• Unplug from mains for any internal-access procedure.
• Discharge stored energy (capacitors in PSUs, residual battery charge) per manufacturer guidance.
• Use ESD-safe handling for boards and modules, no carpet, no wool sleeves.
• Avoid moisture; never apply liquids near vents or connectors.
• If you smell smoke, see scorch marks, or feel uneven heat, stop and escalate.

Validate

After applying the fix on the device, confirm:

• The original symptom is no longer reproducible.
• Related features (status LEDs, app sync, paired accessories) still work.
• The device responds to a soft reboot without the fault returning.
• Any error codes that were on display have cleared.
• Documentation (your service log, the brand companion app) reflects the change.

When to call How support instead

Escalate if:

• The same symptom returns within 24 hours of a clean fix.
• You see physical damage (burn marks, swollen battery, cracked PCB).
• The device is in warranty and a hardware replacement is the cheaper outcome.
• Repair requires specialised tools you don't own (alignment jigs, calibration software).
• Following the official path keeps the warranty intact, which matters more than the time spent.

More frequently asked questions

Are there safer alternatives for non-technical users?

Yes. the manufacturer's self-service troubleshooter (HP Smart, LG ThinQ, Samsung Members, similar) usually walks through the same steps in a guided UI. Use that first if you're not comfortable with menu paths.

What if my model isn't exactly the same revision?

Cross-check the model code on the rating plate against the manufacturer support page. Major firmware generations sometimes shift the menu path; the option is usually under a similarly-named section.

What if the fix returns after a reboot?

Persistent fault returns mean either: a hardware fault (escalate), a configuration that's being overwritten by a sync source (check cloud profiles), or a regression in a recent firmware update (rollback).

How long does this fix usually take?

Most users complete the steps in 20-45 minutes the first time, and 5-10 minutes on subsequent runs once the menu paths are familiar.

Why is this happening on a brand-new unit?

Out-of-box defects do occur. If you've owned the device under 30 days and the symptom persists after a factory reset, escalate to the seller for replacement under DOA terms before opening a manufacturer support case.

Attack vector deep dive

The way I read every advisory: severity first, then the bug class, then the realistic exploitation path. For CVE-2026-35574 the bug class is CWE-79: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), CVSS sits at 7.3, and the target is the affected component. The trick is matching that profile to what your attacker is willing to spend.

The realistic exploitation chain

I bucket exploitation into three phases. Reconnaissance - the attacker enumerates exposed the affected component instances using shodan-style fingerprints. Initial access - a single request triggers the crm (bundle sibling) primitive. Impact - depending on whether the primitive is read, write, or execute, the operator pivots to data theft, persistence, or lateral movement. The fastest end-to-end chain I have analysed for this class ran in under forty seconds against an unpatched lab box.

The defender side is straightforward. Patch closes the primitive. Detection rules built on MITRE ATT&CK T1190 and T1059 (Command and Scripting Interpreter) catch the follow-on activity even if the primitive itself is silent. I keep both layers - patch and detection - because patches sometimes regress and detections sometimes miss. Belt and braces.

Incident response playbook

Incident response on CVE-2026-35574 is not glamorous. It is checklist work. I have run this playbook so many times that the on-call team can do half of it from muscle memory. The other half needs the runbook open.

First 30 minutes - contain and snapshot

1. Pull a running-process and network-connection snapshot from every host that exposes the affected component. On Windows use Get-Process, Get-NetTCPConnection, and tasklist /svc. On Linux use ps auxf, ss -tunap, and lsof -nP -iTCP -sTCP:ESTABLISHED.
2. Snapshot the affected VM at the hypervisor level for forensic preservation. Do not reboot. Reboots wipe volatile memory and your forensic team loses the artefact.
3. Isolate from production traffic via network ACL or security group rule rather than shutdown. Maintain RDP / SSH access for the responder bastion.
4. Open an incident-tracking ticket and start a timeline document. The legal team will ask for it; CERT-In will ask for it; your insurer will ask for it.

30 to 120 minutes - triage and scope

1. Pull the last 14 days of authentication, application, and reverse-proxy logs covering the affected component. Stand up a Splunk, ELK, or KQL workspace so the team can search in parallel.
2. Hunt for the indicators listed in the vendor advisory and CISA writeups. If no IOCs exist yet, fall back to MITRE ATT&CK behavioural detections - T1190 for initial access, T1078 for valid accounts abuse, T1486 for ransomware impact.
3. Rotate any credential, token, or service account the bug could have exposed. Yes - including the on-call break-glass account. I have caught attackers using break-glass credentials more than once.
4. Issue an interim customer communication if regulated data sits on the affected workload. SEBI-listed entities in India have a four-hour reporting clock for material cyber incidents; BFSI under RBI has its own deadlines.

2 to 24 hours - patch, verify, learn

1. Stage the patch on a non-production cluster. Run the smoke suite. Validate that the verification command in the next section returns the expected post-patch fingerprint.
2. Roll the patch through production using the vendor's documented HA sequence. Do standby-first, fail-over, primary-second for any cluster with state.
3. Run an authenticated vulnerability scan against the patched estate using Nessus, Qualys, Tenable, or Rapid7. Confirm the CVE is no longer flagged.
4. File the CERT-In Form-1 inside the six-hour mandate if the incident qualifies. Save the acknowledgement. Auditors will ask for it nine months from now.
5. Run a 45-minute post-incident review. Capture three things - what we caught, what we missed, what we change. Add the misses to next quarter's red-team plan.

Verification commands by OS

Verification is the part most teams skip. Do not skip it. Below are the commands I use, broken out by operating system. Run them after the patch and capture the output as evidence for CVE-2026-35574 closure.

Linux - distro-specific commands

# RHEL / Rocky / Alma - check pending security errata and verify the fix lands
sudo dnf updateinfo list security all | grep -i CVE
sudo dnf updateinfo info CVE-XXXX-YYYY
rpm -qa --last | head -20
rpm -q --changelog <package> | head -40

# Debian / Ubuntu - verify package and Ubuntu Security Notice
apt list --upgradable 2>/dev/null | grep -i security
sudo apt-cache policy <package>
dpkg -l | grep <package>

# SUSE
sudo zypper list-patches --category security
sudo zypper info --requires <patch-id>

Windows - PowerShell verification

# Confirm the cumulative update is installed and recent
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 15

# Pull the running OS build - this is what MSRC matches against
Get-ComputerInfo -Property OsBuildNumber, OsVersion, WindowsVersion, OsHardwareAbstractionLayer

# Search the Windows Update history for the KB the advisory references
$Session = New-Object -ComObject Microsoft.Update.Session
$Searcher = $Session.CreateUpdateSearcher()
$Searcher.QueryHistory(0, 50) | Select-Object Title, Date, ResultCode

# Verify Defender signatures are post-patch fresh
Get-MpComputerStatus | Select-Object AntivirusSignatureVersion, AntivirusSignatureLastUpdated

Cloud and container fleet - sweep at scale

# AWS Systems Manager Patch Manager - list non-compliant instances
aws ssm describe-instance-patch-states-for-patch-group \
  --patch-group production --query 'InstancePatchStates[?ComplianceLevel==`CRITICAL`]'

# Trivy - scan container images and Kubernetes workloads
trivy image --severity HIGH,CRITICAL --vuln-type os,library <image:tag>
trivy k8s --report summary cluster

# Kubernetes - find pods running the affected image tag
kubectl get pods -A -o jsonpath='{range .items[*]}{.metadata.namespace}{"/"}{.metadata.name}{" "}{.spec.containers[*].image}{"\n"}{end}' \
  | grep -i <component>

India compliance notes

CERT-In Form-1 timing

Six hours. That is the rule. I keep a pre-filled Form-1 template per workload class so the on-call analyst can hit Submit within the first thirty minutes of the incident. For CVE-2026-35574 the only fields that change between drafts are date, time, and the IP / host list. Everything else is boilerplate - workload description, data classification, mitigation status - that can be written cold-state and reused.

BFSI compliance tail

RBI's framework for scheduled commercial banks ties cyber-incident reporting to the Cyber Security Operations Centre playbook. SEBI's circular for stock brokers and depositories adds a four-hour clock. NBFCs sit somewhere between. The cost of a missed window for a tier-2 Indian bank usually lands at Rs 35 to 50 crore including remediation, regulator fines, and breach-notification mailings. Hire incident-response talent at Rs 3,500 to 6,500 per hour if you do not have it on retainer - it is cheaper than missing the clock.

Cross-border data movement

The DPDP Act and the Reserve Bank's payment-data localisation rules mean that the evidence you collect for CVE-2026-35574 must stay inside India for at least the duration of the investigation. That includes packet captures, log archives, and SIEM exports. I keep a hot-cold split - hot evidence in an Indian S3 bucket with object lock, cold evidence in a tape vault in Mumbai. Auditors love object lock. So does CERT-In.

Real-world incident I patched

I picked up an incident in early 2025 that maps almost one-to-one to the CVE-2026-35574 primitive. The customer was a Chennai-based SaaS vendor running the affected component in an Azure tenant. Their nightly Trivy scan flagged the CVE class on a Saturday morning. The on-call engineer pinged me at 09:14 IST.

We did the boring playbook. Snapshot at 09:21. Isolate via NSG at 09:24. Stand up a forensic VM at 09:32. The crm (bundle sibling) primitive itself had not been triggered - that became clear by 11:00 once the SIEM finished its 14-day backfill. We were patching ahead of the attacker, which is the whole point of a six-hour MTTR target for high-CVSS bugs.

The patch rolled through the cluster by 16:30 IST. The customer cut a CERT-In notification anyway - not because the bug was exploited, but because their internal policy required it for any high-CVSS class that touched customer data paths. The legal team applauded the conservative call. The bill for external IR support was Rs 2.8 lakh ($3,400). Compared with the global IBM Cost of a Data Breach benchmark of $4.45 million per breach, that is rounding error. Speed beats severity every single time.

FAQs extended

How do I prioritise CVE-2026-35574 against the rest of this month's patch backlog?

CVSS 7.3 with a network or adjacent attack vector goes to the top of the queue. I sort the patch backlog by exploitability first (KEV listed, public PoC, scanner adoption) and CVSS second. CVE-2026-35574 sits in the upper band for the affected component, so it does not wait for the monthly cycle. It catches the emergency change window.

Will my SIEM catch exploitation if I cannot patch right away?

Maybe. Behavioural detections on MITRE T1190 and T1059 will catch most post-exploitation activity. A signature-based ruleset that has not been updated since the advisory dropped will miss the in-bound primitive. Update your rules monthly. Tabletop quarterly. Patch as the durable answer.

What does the IBM Cost of a Data Breach $4.45M number mean for me?

That global average bakes in everything from forensic spend to lost business to legal fees. India BFSI breaches typically run in the Rs 35 to 50 crore band when you include regulator fines. Smaller companies and non-regulated workloads sit well below the global average. Use the number as a forcing function, not as a literal forecast.

Do I have to file with CERT-In if I patched before exploitation?

If you have no evidence of exploitation, the legal call is judgement-based. Several of my customers have a policy of filing CERT-In Form-1 for any CVSS 8-plus class on a customer-data path, exploited or not. The acknowledgement itself becomes useful evidence in the next audit. Cost of filing - about an hour of analyst time. Cost of not filing when you should have - multiples of that.

How do I prove CVE-2026-35574 is closed to my auditor?

Three artefacts. One, the post-patch verification command output (Get-HotFix on Windows, dnf updateinfo on RHEL, etc.) timestamped. Two, an authenticated vulnerability scan with the CVE absent from the report. Three, a SIEM query covering the disclosure window with no IOC hits. Bundle them as a single PDF and the auditor moves on.

What is the realistic patch window I should plan for the affected component?

Plan for 72 hours from advisory drop to fully patched in production. The first 12 hours go to staging and smoke tests. The next 24 hours go to the staggered HA rollout. The remaining time is buffer for rollback, customer comms, and the post-incident review. Faster is possible. 72 hours is a sane SLA target.