CVE-2024-2511 — Unbounded memory growth with session handling in TLSv1.3
Issue summary: Some non-default TLS server configurations can cause unbounded memory growth when processing TLSv1.3 sessions Impact summary: An attacker may exploit certain server configurations to trigger unbounded memory growth that would lead to a Denial of Service This problem can occur in TLSv1.3 if the non-default SSL_OP_NO_TICKET option is being used (but not if early_data support is also configured and the default anti-replay protection is in use). In this case, under certain conditions, the session cache can get into an incorrect state and it will fail to flush properly as it fills. The session cache will continue to grow in an unbounded manner. A malicious client could deliberately create the scenario for this failure to force a Denial of Service. It may also happen by accident in normal operation. This issue only affects TLS servers supporting TLSv1.3. It does not affect TLS clients. The FIPS modules in 3.2, 3.1 and 3.0 are not affected by this issue. OpenSSL 1.0.2 is also not affected by this issue.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 52.4% (30-day exploitation probability)+15
- Technical severity (medium)+3
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.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
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.
- Identify exposed assets running the affected vendor/product/version combinations (Openssl Openssl).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- EPSS ahead of 99% of scored CVEs: prioritize it in the patch queue.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 5.9 | CVSS 3.1 | Medium | 2.2 | 3.6 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database |
| 5.9 | CVSS 3.1 | Medium | — | — | GitHub, Inc. via GitHub Security Advisories |
| 5.9 | CVSS 3.1 | Medium | — | — | CISA-ADP via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: 134c704f-9b21-4f2e-91b3-4a467353bcc0) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
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).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · openssl/openssl
- SSVC assessment updated
- Record published
- CVSS changed · 5.9
- Source status changed · → Deferred
- Record created in this database
- 2024
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 14, 2026 – Oct 14, 2026
References
18 on the record
- github.com/openssl/openssl/commit/e9d7083e241670332e0443da0f0d4ffb52829f08
- github.openssl.org/openssl/extended-releases/commit/5f8d25770ae6437db119dfc951e207271a32
- github.com/openssl/openssl/commit/7e4d731b1c07201ad9374c1cd9ac5263bdf35bce
- github.com/openssl/openssl/commit/b52867a9f618bb955bed2a3ce3db4d4f97ed8e5d
- github.com/advisories/GHSA-299c-jvhc-gxj8
- cert-portal.siemens.com/productcert/html/ssa-265688.html
- www.openssl.org/news/secadv/20240408.txt
- cert-portal.siemens.com/productcert/html/ssa-915275.html
- security.netapp.com/advisory/ntap-20240503-0013/
- lists.debian.org/debian-lts-announce/2024/10/msg00033.html
- cert-portal.siemens.com/productcert/html/ssa-613116.html
- nvd.nist.gov/vuln/detail/CVE-2024-2511
- www.openwall.com/lists/oss-security/2024/04/08/5
- cert-portal.siemens.com/productcert/html/ssa-398330.html
- cert-portal.siemens.com/productcert/html/ssa-769027.html
- cert-portal.siemens.com/productcert/html/ssa-354112.html
- lists.debian.org/debian-lts-announce/2024/11/msg00000.html
- security.netapp.com/advisory/ntap-20240503-0013
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-84783 Use-After-Free in X.509 Extension Cache Under Concurrent Use 16d
- High CVE-2026-84784 QUIC: Unbounded RETIRE_CONNECTION_ID Backlog 16d
- High CVE-2026-84782 DTLS Retransmits Handshake Messages From a Stale Buffer Offset 16d
- Medium CVE-2026-75805 NULL Pointer Dereference in CMP Client Revocation Response Handling 16d
- Medium CVE-2026-75806 Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS 16d
- Low CVE-2026-77696 Timing Side-Channel in SM2 Signature Generation 16d
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 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-2024-2511 is "Unbounded memory growth with session handling in TLSv1.3", rated Medium. It affects Openssl (Openssl); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.9 describes technical severity. EPSS 52.42% 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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