Unsafe Deserialization in seroval (CVE-2026-59940)
Summary
Vulnerability in seroval (CVE-2026-59940). Successful exploitation can lead to full system takeover. Exploitable via seroval. Mitigation: upgrade to 1.5.3 or later.
Original description
The description as published by the source.
Summary
A type confusion issue in seroval.fromJSON() allowed attacker-controlled JSON input to cause Promise control nodes to operate on values from the general deserialization reference table without first verifying that those values were genuine internal promise resolver records.
In applications that deserialize untrusted Seroval JSON with plugins enabled, this could allow attacker-controlled deserialization side effects. In downstream server frameworks that register plugins returning callable wrappers, this primitive could become unintended server-side invocation and, depending on exposed application functionality, remote code execution or equivalent server compromise.
The issue was fixed in seroval@1.5.3.
Affected package
- Package:
seroval - Affected API:
fromJSON() - Affected versions: versions prior to
1.5.3that contain the vulnerable Promise resolver reference handling - Patched version:
1.5.3
Impact
The vulnerable deserialization path could confuse attacker-created values in the general reference table with Seroval's internal promise resolver records.
Direct impact in seroval is a deserialization side-effect primitive when untrusted JSON is deserialized with plugins enabled. Downstream impact depends on registered plugins and framework usage. If a downstream framework registers plugins that deserialize sensitive callable wrappers, attacker-controlled input may be able to trigger unintended server-side invocation during deserialization.…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-59940 has been found in seroval.
Attackers can target a specific entry point like seroval over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade seroval to 1.5.3 or later.
If unsure, ask your IT team or search "seroval CVE-2026-59940" on the vendor's site.
CVE-2026-59940 (seroval) — CWE-502 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: seroval
Patched: 1.5.3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Unsafe deserialization (CWE-502) exists in seroval. Attackers reach the vulnerable code path via seroval without authentication.
Check the vendor advisory for the affected versions of seroval. Attack surface: seroval.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to 1.5.3.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'seroval' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'seroval' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
serovalを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade seroval to 1.5.3ステージング環境で 1.5.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web npmjs.com
- web github.com