Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by opening and holding open a large number of connections. The max_clients option is documented to default to 150, and the inets hardening guide presents that limit as the first layer of denial-of-service defence, but a server that does not set it explicitly accepts an unlimited number of simultaneous connections. Establishing the connections is sufficient; no valid request and no authentication are required.
The accept gate in httpd_manager:handle_new_connection/4 reads the option with httpd_util:lookup/2, which returns undefined when the key is absent, rather than the three-argument form carrying the 150 default that the neighbouring get_ustate/2 uses. Erlang term ordering places every integer before every atom, so the Count =< Max guard holds for any connection count and the server never returns {reject, busy}. Each accepted connection occupies a worker process and a socket for as long as it is held, driving the node towards process, memory and file descriptor exhaustion. Servers that set max_clients explicitly are unaffected, because a configured value is applied as intended.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, OTP 28.5.0.6, and OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, 9.6.2.3, and 9.7.2.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.7): severity, escalated by confirmed exploitation. This CVE's 8.7 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.7 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source
- EG Likelihood
- 0.9% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it