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PatchSiren cyber security CVE debrief

CVE-2024-2511 OpenSSL CVE debrief

CVE-2024-2511 affects certain OpenSSL TLSv1.3 server configurations, not clients. In the risky case, using the non-default SSL_OP_NO_TICKET option can leave the session cache in an incorrect state so it fails to flush as it fills, allowing unbounded memory growth and a denial of service. OpenSSL says the issue does not occur when early_data is configured with the default anti-replay protection, and that FIPS modules in 3.2/3.1/3.0 and OpenSSL 1.0.2 are not affected.

Vendor
OpenSSL
Product
OpenSSL
CVSS
LOW 3.7
CISA KEV
Not listed in stored evidence
Original CVE published
2025-08-12
Original CVE updated
2026-02-25
Advisory published
2025-08-12
Advisory updated
2026-02-25

Who should care

Operators and security teams running OpenSSL-backed TLS servers with TLSv1.3, especially those using non-default session ticket settings such as SSL_OP_NO_TICKET.

Technical summary

The flaw is a server-side TLSv1.3 session-cache state bug. Under certain conditions, disabling session tickets with SSL_OP_NO_TICKET can prevent the cache from flushing correctly as it grows, leading to unbounded memory consumption. The NVD record maps the issue to CWE-1325 and lists a network-accessible denial-of-service impact only.

Defensive priority

Medium

Recommended defensive actions

  • Inventory TLSv1.3 servers using OpenSSL and check for SSL_OP_NO_TICKET in production configurations.
  • Review whether early_data and default anti-replay protection are enabled; avoid the vulnerable configuration path described in the advisory.
  • Apply the OpenSSL fix from the vendor advisory and related commits on affected deployments.
  • Monitor server memory and session-cache behavior for unexpected growth after TLS configuration changes.
  • Confirm that TLS clients and unaffected builds are excluded from remediation scope, but still validate server-side deployments.

Evidence notes

Source evidence includes the OpenSSL security advisory dated 2024-04-08, the CVE record, and NVD metadata. The corpus states the issue impacts certain TLSv1.3 servers using non-default SSL_OP_NO_TICKET, is not a client issue, and does not affect OpenSSL 1.0.2 or FIPS modules in 3.0/3.1/3.2. NVD lists CVSS 3.1 vector AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H with score 5.9 and marks the record Deferred.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-2511 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-2511

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2024-2511 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-2511

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2025/icsa-25-226-15.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-613116.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-613116.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-226-15

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-alerts/ics-alert-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/topics/industrial-control-systems

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf

    Reference

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.