CVE-2024-2511Network attack vector

Remote denial of service via unbounded session cache

Published Apr 8, 2024 · Updated May 12, 2026

Denial of service in OpenSSL 1.1.1 and 3.0 through 3.2 allows remote attackers to exhaust TLS 1.3 server memory. With SSL_OP_NO_TICKET enabled, affected session handling leaves the cache in an incorrect state and fails to flush entries as it fills. Exposure requires a TLS 1.3 server using that non-default option, except when early data and default anti-replay protection are both active; clients and FIPS modules are unaffected.

CVSS severity3.7
Low
EPSS probability54.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in OpenSSL 1.1.1 and 3.0 through 3.2 allows remote attackers to exhaust TLS 1.3 server memory. With SSL_OP_NO_TICKET enabled, affected session handling leaves the cache in an incorrect state and fails to flush entries as it fills. Exposure requires a TLS 1.3 server using that non-default option, except when early data and default anti-replay protection are both active; clients and FIPS modules are unaffected.

The record

CVE
CVE-2024-2511
Published
Apr 8, 2024
Updated
May 12, 2026
Vendor
Siemens
Product
SCALANCE MUM856-1 (RoW)
Classifications
CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 8, 2024CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <V8.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SCALANCE MUM856-1 (RoW)version=0 <V8.2
Siemens · SCALANCE MUM856-1 (B1)version=0 <V8.2
Siemens · SCALANCE MUM856-1 (EU)version=0 <V8.2
Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · RUGGEDCOM RM1224 LTE(4G) NAMversion=0 <V8.2
Siemens · RUGGEDCOM RM1224 LTE(4G) EUversion=0 <V8.2
Siemens · SCALANCE M874-3version=0 <V8.2
Siemens · SCALANCE MUM856-1 (A1)version=0 <V8.2
Siemens · SCALANCE MUM853-1 (B1)version=0 <V8.2
Siemens · SCALANCE MUM856-1 (CN)version=0 <V8.2
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
Siemens · SCALANCE M812-1 ADSL Routerversion=0 <V8.2
Siemens · SCALANCE S615 EEC LAN Routerversion=0 <V8.2
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SCALANCE M826-2 SHDSL-Routerversion=0 <V8.2
Siemens · SCALANCE M816-1 ADSL Routerversion=0 <V8.2
Siemens · SCALANCE M876-3 (ROK)version=0 <V8.2
Siemens · SCALANCE M876-3version=0 <V8.2
Siemens · SCALANCE XCM/XRM/XCH/XRH-300 familyversion=0 <V3.1
Siemens · SCALANCE MUM853-1 (A1)version=0 <V8.2
Siemens · SCALANCE M804PBversion=0 <V8.2
OpenSSL Project · OpenSSLversion=1.1.1 <1.1.1y; version=3.0.0 <3.0.14; version=3.1.0 <3.1.6; version=3.2.0 <3.2.2
Siemens · RUGGEDCOM RST2428Pversion=0 <V3.1
Siemens · SCALANCE M876-4version=0 <V8.2
Siemens · SCALANCE M876-4 (NAM)version=0 <V8.2
Siemens · SCALANCE MUM853-1 (EU)version=0 <V8.2
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SCALANCE S615 LAN-Routerversion=0 <V8.2
Siemens · SCALANCE M876-4 (EU)version=0 <V8.2
Siemens · SCALANCE M874-3 3G-Router (CN)version=0 <V8.2
Siemens · SCALANCE M874-2version=0 <V8.2

Published CVSS scores

3.7Siemens ProductCERTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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