VulnerabilityPublished 13 Nov 2026

CVE-2026-123635: elixir-grpc grpc_server · Missing Release of Resource after Effective Lifetime

Affects elixir-grpc grpc_serverSource CVE Database V5

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Not known to be exploited · CVSS 6.3 Medium : upgrade to 1.1.0 when convenient.

Data as of 13 Nov 2026, 15:49 UTC

CVSS 4.0 base score

6.3Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (EEF)	CVSS 4.0	6.3

Patch: Available – fixed in 1.1.0, 61a71948e6e7b95efb27d48e7084c764503cc802

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade grpc_server to 1.1.0; grpc_server to 61a71948e6e7b95efb27d48e7084c764503cc802.

Affected software

Product	Affected	Fixed in
elixir-grpcgrpc_server	Affected >=1.0.0 <1.1.0	Fixed in 1.1.0
grpc_serverelixir-grpc/grpc	Affected ≥ 0332faae5f5e132314794dbfdae5edecbccea292, < 61a71948e6e7b95efb27d48e7084c764503cc802	Fixed in 61a71948e6e7b95efb27d48e7084c764503cc802
Hexgrpc_server`pkg:hex/grpc_server`Other threats	Affected >=1.0.0 <1.1.0	Fixed in 1.1.0

CPE configurations (1)

cpe:2.3:a:elixir-grpc:grpc_server:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade grpc_server to version 1.1.0 or later, where this issue is fixed. No other mitigation is indicated.

Description

CVE-2026-123635 is a resource management vulnerability in elixir-grpc grpc_server versions from 1.0.0 up to but not including 1.1.0. It allows a client to stall all subsequent calls on a shared HTTP/2 connection by sending calls that the server refuses while their DATA frames are still in flight. This causes the connection's flow-control window to be depleted, blocking further request bodies on that connection until deadlines expire. Other connections remain unaffected. The issue is fixed in version 1.1.0.

Impact

An attacker can cause denial of service on a single HTTP/2 connection by stalling all subsequent calls, leading to resource exhaustion on that connection. This does not affect other connections. The impact is limited to degraded availability of the affected connection.

Summary

The vulnerability arises because the grpc_stream_h handler in grpc_server requests flow control only for request data that has arrived. When the server refuses a call early (e.g., due to exceeding max_body_size or unsupported method), Cowboy drops the in-flight DATA frames for that stream without returning their bytes to the connection flow-control window. This leads to depletion of the flow-control window after multiple refused calls, stalling all later calls on that HTTP/2 connection. The problem affects grpc_server versions >=1.0.0 and <1.1.0 and is addressed in version 1.1.0.

CWE-772Missing Release of Resource after Effective Lifetime (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation
It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free resources in a function. If you allocate resources that you intend to free upon completion of the function, you must be sure to free the resources at all exit points for that function including…
Operation · Architecture and Design · Resource Limitation
Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available.
Attack patterns
HTTP DoS (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

CPE configurations (1)

Description

AI analysisMachine-generated, updated 13 Nov 2026, 15:49 UTC

WeaknessesCWE-772

Technical details

References

Community reviews

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