OpenSSL 1.1.1 < 1.1.1y Multiple Vulnerabilities

This plugin bundles two OpenSSL 1.1.1 flaws fixed in 1.1.1y. CVE-2024-2511 (CVSS 5.9) causes unbounded memory growth in TLSv1.3 session caches — but *only* on servers that set the non-default SSL_OP_NO_TICKET option without early_data support. CVE-2024-4741 is a use-after-free in SSL_free_buffers() — but that function is explicitly documented as rarely called by applications, and only those that directly invoke it are affected. Both CVEs affect OpenSSL 1.1.1 through 1.1.1x, fixed in 1.1.1y (available only through premium extended support since 1.1.1 went EOL on 2023-09-11).

Tenable's plugin rolls both into a CVSS 7.5 / HIGH rating, which dramatically overshoots reality. OpenSSL's own security team rated both CVEs as Low severity. The 7.5 score appears to come from a generic network-reachable availability-impact vector that ignores the non-default configuration prerequisites. The vendor (OpenSSL) is the authority on its own code's exploitability here, and they say Low — twice. The real risk conversation for hosts running OpenSSL 1.1.1 isn't these specific CVEs; it's the EOL status and the absence of future public patches.

Why this verdict

• Non-default prerequisites slash reachable population. CVE-2024-2511 requires SSL_OP_NO_TICKET *without* early_data — a configuration almost no production TLS server uses. CVE-2024-4741 requires the application to directly call SSL_free_buffers(), which OpenSSL documents as rarely used. These preconditions reduce the actually-vulnerable population to well under 5% of the OpenSSL 1.1.1 install base.
• Vendor self-assessment is Low × 2. OpenSSL's own security team — the people who wrote the code — rated both CVEs as Low. Tenable's 7.5 score ignores the configuration prerequisites and applies a generic network-availability vector. We follow the vendor's judgment here.
• No exploitation evidence or tooling. Zero PoCs, zero KEV listing, zero campaign reports. The UAF (CVE-2024-4741) is theoretically more dangerous but without a weaponization path demonstrated, it remains theoretical.
• Role multiplier: OpenSSL is a foundational library present in high-value roles (network edge appliances, load balancers, web servers, identity providers). However, the chain only succeeds if the specific non-default config or rare API call is present. For CVE-2024-2511, the blast radius is DoS only (availability, no confidentiality/integrity impact) — a restart recovers the service. For CVE-2024-4741, theoretical RCE exists but requires the rare SSL_free_buffers() call pattern. Even in high-value roles, the precondition filter means <5% of installs are plausibly reachable, which is below the ≥10% threshold for a canonical high-value-role floor. The floor does not engage.
• DoS-only impact for the more reachable CVE. CVE-2024-2511 can only cause memory exhaustion (availability impact). It cannot lead to code execution, data exfiltration, or lateral movement. This caps its severity regardless of where OpenSSL is deployed.

Why not higher?

Upgrading to MEDIUM would require either a demonstrated exploitation path or a significantly larger reachable population. The non-default config requirements are not soft suggestions — they are hard code-path gates. Without SSL_OP_NO_TICKET set, CVE-2024-2511's vulnerable code path is never reached. Without calling SSL_free_buffers(), CVE-2024-4741 is dead code. No PoC exists for either.

Why not lower?

An IGNORE verdict would require zero plausible impact. CVE-2024-4741 is a use-after-free — a vulnerability class with a history of surprising weaponization. While the preconditions are narrow, we cannot rule out that some niche but important application calls SSL_free_buffers(). Additionally, OpenSSL 1.1.1's EOL status means the finding signals a broader hygiene problem that deserves tracking even if these specific CVEs are low-risk.

1. Prioritize migration off OpenSSL 1.1.1 entirely — The real risk is not these two CVEs — it's running an EOL cryptographic library. Begin planning migration to OpenSSL 3.0.x or 3.2.x+ within the noisgate remediation SLA of 365 days for LOW findings. This eliminates current and all future 1.1.1 findings at once.
2. Verify SSL_OP_NO_TICKET and SSL_free_buffers usage — Audit your applications for use of SSL_OP_NO_TICKET (grep source or config) and SSL_free_buffers() (grep source / symbol tables). If neither is present, these CVEs are non-exploitable in your environment. Document the finding and deprioritize.
3. Apply distro-backported patches where available — RHEL, Ubuntu, Debian, and SUSE have backported fixes for these CVEs into their supported OpenSSL packages. Run your OS package manager update — this is faster than upgrading the OpenSSL major version. No mitigation SLA applies for LOW, but this is easy hygiene.
4. Ensure process supervision and memory limits on TLS services — For CVE-2024-2511, configure systemd MemoryMax or equivalent cgroup limits on TLS-serving processes. A process supervisor that restarts on OOM contains the DoS impact to seconds of downtime.

Run on each target host where OpenSSL 1.1.1 may be installed. Execute as any user with read access to the openssl binary: bash check_openssl_192965.sh

#!/usr/bin/env bash
# check_openssl_192965.sh — Tenable 192965 / CVE-2024-2511, CVE-2024-4741
# Checks whether OpenSSL 1.1.1 is below 1.1.1y
# Exit codes: 0 = PATCHED/NOT_AFFECTED, 1 = VULNERABLE, 2 = UNKNOWN

set -euo pipefail

OPENSSL_BIN="${1:-openssl}"

if ! command -v "$OPENSSL_BIN" &>/dev/null; then
  echo "UNKNOWN — openssl binary not found at '$OPENSSL_BIN'"
  exit 2
fi

VERSION_STR=$("$OPENSSL_BIN" version 2>/dev/null || true)

if [[ -z "$VERSION_STR" ]]; then
  echo "UNKNOWN — could not determine OpenSSL version"
  exit 2
fi

# Check if it's OpenSSL 1.1.1
if [[ "$VERSION_STR" =~ OpenSSL\ 1\.1\.1([a-z]?) ]]; then
  LETTER="${BASH_REMATCH[1]}"
  # 1.1.1y = letter 'y' (25th letter). Letters a-x are vulnerable.
  if [[ -z "$LETTER" ]]; then
    # Plain 1.1.1 with no letter — vulnerable
    echo "VULNERABLE — $VERSION_STR (pre-1.1.1y)"
    exit 1
  fi
  # Convert letter to number (a=1, b=2, ... y=25)
  LETTER_NUM=$(printf '%d' "'$LETTER")
  LETTER_NUM=$((LETTER_NUM - 96))  # a=1
  if (( LETTER_NUM < 25 )); then
    echo "VULNERABLE — $VERSION_STR (pre-1.1.1y)"
    exit 1
  else
    echo "PATCHED — $VERSION_STR (1.1.1y or later)"
    exit 0
  fi
elif [[ "$VERSION_STR" =~ OpenSSL\ 3\. ]]; then
  echo "PATCHED — $VERSION_STR (OpenSSL 3.x, check separately for 3.x-specific fixes)"
  exit 0
else
  echo "UNKNOWN — not OpenSSL 1.1.1 series: $VERSION_STR"
  exit 2
fi

Sources

1. Tenable Plugin 192965
2. OpenSSL 1.1.1 Vulnerabilities List
3. CVE-2024-2511 — OSV
4. CVE-2024-4741 — Snyk
5. OpenSSL 1.1.1 EOL Announcement
6. CVE-2024-4741 — Red Hat Bugzilla
7. Rapid7 — CVE-2024-2511