CVE Intelligence
High Denial of service

CVE-2026-86696 — Unbounded atom creation from unsigned LogoutResponse status codes in esaml allows atom table exhaustion

Allocation of Resources Without Limits or Throttling vulnerability in esaml in dropbox esaml allows an unauthenticated attacker to exhaust the Erlang VM atom table and crash the node via unsigned LogoutResponse messages. esaml:status_code_map/1 in src/esaml.erl maps any StatusCode value it does not recognize to an atom with list_to_atom/1 on the last colon-separated segment of the URN. esaml_sp:validate_logout_response/2 verifies a signature only when the message carries one, so an unsigned LogoutResponse posted to the single-logout endpoint reaches esaml:decode_logout_response/1 and mints one permanent atom per distinct status value. Atoms are never reclaimed and the VM caps the atom table at about one million entries, so an attacker who posts that many distinct values aborts the node. This issue affects esaml: from 0.1.0 onward.

Published Oct 22, 2026 · Updated Oct 22, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database · CNA: EEF

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.4% (30-day exploitation probability)+6
  • Technical severity (high)+6

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.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.44%
ahead of 37% of scored CVEs · Oct 22, 2026
Affects
Arekinath
Esaml
CVSS base
8.2
High · 2 source(s)

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.

  1. Identify exposed assets running the affected vendor/product/version combinations (Arekinath Esaml, Dropbox Esaml, Handnot2 Esaml).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. 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.

VendorProductVersionsStatusSource
Arekinath Esaml ≥ be692b56245071899757afa7ef47e43593d3de96 Vulnerable CVE Program (cve.org) e CISA ADP
Dropbox Esaml ≥ 0.1.0≥ be692b56245071899757afa7ef47e43593d3de96 Vulnerable CVE Program (cve.org) e CISA ADP
Handnot2 Esaml ≥ be692b56245071899757afa7ef47e43593d3de96 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Attack requirements
Present
Privileges required
None
User interaction
None
Scope
X
Confidentiality (vulnerable system)
None
Integrity (vulnerable system)
None
Availability (vulnerable system)
High
Confidentiality (subsequent)
None
Integrity (subsequent)
None
Availability (subsequent)
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.2 CVSS 4.0 High — — 6b3ad84c-e1a6-4bf7-a703-f496b71e49db via NIST National Vulnerability Database
8.2 CVSS 4.0 High — — EEF via CVE Program (cve.org) e CISA ADP
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X (score shown at the top: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-770 · Allocation of Resources Without Limits or Throttling

Other CVEs with this weakness →

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.
web/proxy/WAF logsnetwork IDS/IPSresource metrics

Timeline

What happened to this CVE, newest first.

  • 2026
  • Source status changed · Received → Deferred
    Oct 22, 2026 · NIST National Vulnerability Database
  • Source status changed · Published → Received
    Oct 22, 2026 · NIST National Vulnerability Database
  • CVE published
    Oct 22, 2026 · EEF
  • Record published
    Oct 22, 2026
  • CVSS changed · 8.2
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 22, 2026 – Oct 22, 2026

References

5 on the record

Elsewhere on this site

Arekinath
every CVE for this vendor
Denial of service
same class
CWE-770
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-93471 Unbounded SAML message decompression in esaml allows memory exhaustion 1d
  • CVE-2026-105270 Unbounded atom creation while parsing SAML messages in esaml allows atom table exhaustion 1d
  • CVE-2026-28809 XXE in esaml SAML library allows local file read and potential SSRF Mar 23, 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 fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • 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-2026-86696 is "Unbounded atom creation from unsigned LogoutResponse status codes in esaml allows atom table exhaustion", rated High. It affects Esaml (Arekinath); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.2 describes technical severity. EPSS 0.44% estimates the probability of exploitation in 30 days; neither replaces your asset context. 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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