CVE-2026-87908 — multiparty vulnerable to Denial of Service via unbounded part-header accumulation
multiparty is a Node.js library for parsing multipart/form-data request bodies. In versions from 2.1.0 up to but not including 4.3.1, the parser does not bound the amount of memory used while accumulating the headers of a single multipart part. An unauthenticated attacker can send a single request whose part carries a very large volume of header bytes, forcing the parser to buffer all of them and exhausting the process memory, which crashes the server. This is a denial of service with no confidentiality or integrity impact. The issue is fixed in multiparty 4.3.1, which caps the size of the accumulated part headers. Users should upgrade to multiparty 4.3.1 or later.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (high)+6
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Multiparty Multiparty).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Multiparty | Multiparty | ≥ 2.1.0 and < 4.3.1 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.5 | CVSS 3.1 | High | 3.9 | 3.6 | ce714d77-add3-4f53-aff5-83d477b104bb via NIST National Vulnerability Database |
| 7.5 | CVSS 3.1 | High | — | — | openjs via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: ce714d77-add3-4f53-aff5-83d477b104bb) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Track CPU/memory spikes and availability drops correlated with request patterns.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · multiparty/multiparty
- SSVC assessment updated
- Record published
- CVSS changed · 7.5
- Source status changed · → Awaiting Analysis
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-8162 multiparty vulnerable to Denial of Service via Uncaught Exception in filename* parameter parsing May 12, 2026
- High CVE-2026-8159 multiparty vulnerable to ReDoS via filename parsing May 12, 2026
- High CVE-2026-8161 multiparty vulnerable to Denial of Service via Prototype Pollution leading to Uncaught Exception May 12, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-87908 is "multiparty vulnerable to Denial of Service via unbounded part-header accumulation", rated High. It affects Multiparty (Multiparty); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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