Security readout for executives and security teams
Plain-English summary
A weakness in how Node.js stores short text strings lets an attacker send specially crafted data that makes the server work much harder than normal. The result is slower responses or temporary outages, not data theft. Any Node.js app that accepts JSON from the internet is potentially affected, and Node.js has released fixed versions.
Executive priority
Schedule patching during the next standard maintenance window. Prioritize internet-facing Node.js services that parse JSON from untrusted clients to limit availability risk.
Technical view
V8's string hashing maps integer-like strings to their numeric value, producing predictable collisions in the internal string interning table. Attackers can craft JSON payloads that, when parsed by JSON.parse, internalize many colliding short strings, degrading hash table operations to worst-case complexity and exhausting CPU. Affects Node.js 20.x, 22.x, 24.x, and 25.x; fixed in 20.20.1, 22.22.1, 24.14.0, and 25.8.1.
Likely exposure
Any Node.js 20.x, 22.x, 24.x, or 25.x service that calls JSON.parse on attacker-controlled input is exposed. Public APIs, webhooks, GraphQL endpoints, and proxies that accept JSON bodies from untrusted clients are the most likely exposure paths.
Exploitation context
No public reports of active exploitation and not listed in CISA KEV. The flaw enables predictable hash collisions that an attacker can trigger by sending crafted JSON payloads to any endpoint calling JSON.parse on user input, degrading process performance.
Researcher notes
CWE-328 (use of weak hash) applied to V8's internal string interning table. Integer-like strings hash to their numeric value, making collisions trivially predictable. JSON.parse internalizes short strings, which is the practical trigger. CVSS 5.9 (AV:N/AC:H/PR:N/UI:N/A:H) reflects availability-only impact with high attack complexity. Confirm runtime versions across containers, serverless layers, and embedded Node binaries; lambda or worker runtimes may lag upstream releases.
Mitigation direction
- Upgrade Node.js to 20.20.1, 22.22.1, 24.14.0, or 25.8.1 per the March 2026 Node.js security release.
- Inventory services running affected Node.js versions and prioritize internet-facing JSON endpoints.
- Enforce request body size limits and rate limiting on endpoints that accept JSON input.
- Place a WAF or reverse proxy in front of Node.js services to drop oversized or anomalous payloads.
- Monitor Node.js process CPU and event-loop latency to detect degradation incidents.
- Track vendor advisories for any follow-up patches or guidance from the Node.js security team.
Validation and detection
- Run 'node -v' on hosts and containers and compare against fixed releases 20.20.1, 22.22.1, 24.14.0, 25.8.1.
- Inventory endpoints that call JSON.parse on request bodies or query parameters from untrusted sources.
- Review CDN, WAF, and load balancer logs for anomalous large or repetitive JSON payloads.
- Check observability dashboards for unexplained event-loop latency or CPU spikes on Node.js workers.
- Confirm package manifests and Dockerfiles pin to patched Node.js versions after upgrade.
- Validate fixes in staging by load-testing JSON endpoints before promoting to production.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-328: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-21717 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H2.23.6hackeroneVulnerability scoring details
Base CVSS 3.0 score
5.9MediumVector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://nodejs.org/en/blog/vulnerability/march-2026-security-releasesCVE reference, hackerone
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of Weak Hash
Use of Weak Hash represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.