CVE-2026-39901 — monetr
MEDIUMCVE-2026-39901 is a medium-severity (CVSS 5.7) vulnerability in github.com/monetr/monetr. A fix is available for github.com/monetr/monetr — see the affected versions and patch details below.
monetr: Protected Transactions Deletable via PUT
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-39901.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-39901 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/monetr/monetrReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A transaction integrity flaw allows an authenticated tenant user to soft-delete synced non-manual transactions through the transaction update endpoint, despite the application explicitly blocking deletion of those transactions via the normal DELETE path. This bypass undermines the intended protection for imported transaction records and allows protected transactions to be hidden from normal views.
Details
The issue affects the transaction update path for synced transactions associated with non-manual links. The intended policy is clearly enforced in the DELETE handler: deletion of synced transactions for non-manual links is rejected with an error indicating that such transactions cannot be deleted.
However, the PUT update path still accepts a client-controlled full Transaction object and persists fields that should be server-managed, including deletedAt. The update logic appears to restrict only selected fields, which leaves deletedAt attacker-controllable.
Verified behavior on the same synced transaction showed:
DELETEwas denied with the expected protection error for non-manual linksPUTwith a user-supplieddeletedAtvalue succeeded and returned200 OK- a subsequent transaction list no longer showed the transaction
GETby transaction ID still returned the record withdeletedAtpopulated
This demonstrates a policy bypass: although the server explicitly defines synced transactions on non-manual links as non-deletable through the dedicated delete route, the same outcome can still be achieved through the update route by setting the soft-delete field directly.
The vulnerability is therefore not a simple UI inconsistency. It is a server-side authorization and integrity flaw caused by trusting a client-supplied full transaction object and failing to protect sensitive server-managed fields from modification.
PoC
The issue can be reproduced by identifying a synced transaction on a non-manual link, confirming that the normal DELETE route rejects deletion, then submitting an update request that sets the transaction’s deletedAt field. The transaction will then disappear from normal listing views even though direct retrieval still shows the record as soft-deleted.
Impact
- Type: Authorization bypass / integrity violation
- Who is impacted: Authenticated tenant users and any deployment relying on synced transaction immutability for non-manual links
- Security impact: Attackers can hide or effectively delete protected imported transactions that should not be deletable, compromising transaction history, bookkeeping integrity, and trust in audit-relevant server-managed fields
- Attack preconditions: The attacker must be authenticated and able to access a synced transaction within their own tenant/account scope
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/monetr/monetr | all versions | 1.12.3go get github.com/monetr/monetr@v1.12.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/monetr/monetr, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/monetr/monetr to 1.12.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39901 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-39901 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-39901. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-39901 in your dependencies?
O3 Security finds CVE-2026-39901 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.