Issue summary: A malicious TLS server can cause a memory leak in a TLS client that has enabled...
Summary
Vulnerability reported (CVE-2026-54876). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
Issue summary: A malicious TLS server can cause a memory leak in a TLS
client that has enabled OCSP response checking by sending an OCSP
response that contains no single response entries.
Impact summary: An attacker can leak an attacker-tunable amount of memory
per TLS handshake in a victim client application. A long-running client
that repeatedly connects to a malicious server can have its memory
exhausted, resulting in a Denial of Service.
CWE: CWE-401: Missing Release of Memory after Effective Lifetime
Description: The affected function is called during X.509 certificate
chain verification when OCSP response checking is enabled
with the X509_V_FLAG_OCSP_RESP_CHECK or X509_V_FLAG_OCSP_RESP_CHECK_ALL
verification flags, for example when a TLS client verifies an OCSP
response stapled into the TLS handshake by the server.
When the received BasicOCSPResponse contains an empty SEQUENCE OF
SingleResponse, which is permitted on the wire and accepted by the
OpenSSL decoder, the OCSP_BASICRESP structure allocated by
OCSP_response_get1_basic() was not freed because an early return
bypassed the cleanup code at the end of the function.
The amount of memory leaked per handshake can be amplified by the
attacker by padding the certs field of the BasicOCSPResponse with
bogus certificates, which are parsed and stored in the leaked
structure before the empty response check triggers the early return.
A long-running TLS client that repeatedly connects to a malicious
server can have its me…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-54876 has been found.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2026-54876" on the vendor's site.
CVE-2026-54876 — CWE-401 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-401) has been reported.
Check the vendor advisory for the affected versions.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-54876
- Debian DEBIAN-CVE-2026-54876 openssl Fixed in: 3.6.4-1
- Ubuntu UBUNTU-CVE-2026-54876 nodejs
References
- JVN JVNDB-2026-027713
- web nvd.nist.gov
- web openssl-security@openssl.org
- web openssl-security@openssl.org
- web openssl-security@openssl.org
- web github.com
- web openwall.com