CVE-2026-94419
Client session cache reference poisoning allows resumption with wrong server
Description
Without NO_SESSION_CACHE_REF, wolfSSL_get_session() does not return a session object but a ClientSession reference of the form {row, index, hash(sessionID)} into the process-global SessionCache, and ClientSessionToSession() validates it against that hash alone. Because the TLS 1.2 session ID is chosen by the server and sent in clear, AddSessionToCache() matches any other server's session on the same ID and overwrites the client-side entry with that server's master secret, cipher suite and version, while the handle continues to resolve; nothing on the write path compares the peer, the application's server ID or the WOLFSSL_CTX. Resuming through the handle then produces an abbreviated handshake in which no Certificate message is sent, so neither chain verification nor wolfSSL_check_domain_name() runs, and the attacker is accepted as the original server for the whole of that connection. Affected builds are those leaving NO_SESSION_CACHE_REF, NO_SESSION_CACHE, NO_CLIENT_CACHE and TITAN_SESSION_CACHE all undefined, which includes a plain ./configure, --enable-opensslextra and --enable-opensslall; fifteen integration options define NO_SESSION_CACHE_REF and are therefore not affected, among them --enable-all, --enable-distro, --enable-curl, --enable-nginx, --enable-haproxy, --enable-stunnel, --enable-wpas and the rest of the OPENSSL_COMPATIBLE_DEFAULTS family, and --enable-leanpsk, --enable-leantls, --enable-lowresource and --enable-tinytls13 disable the cache outright. The application must use the legacy reference flow, wolfSSL_get_session() or SSL_get_session() followed by wolfSSL_set_session(); wolfSSL_get1_session() returns the session object itself and is not affected, nor are wolfSSL_SetServerID() lookups. Only TLS 1.2 and below and DTLS 1.2 and below are reachable, since TLS 1.3 and ticket resumption with an empty ServerHello session ID both use a client-chosen cache key. The poisoned entry lives in the process-global cache, so it crosses WOLFSSL_CTX boundaries and persists until the entry is evicted or the session times out, 500 seconds by default. Releases v5.3.0 through v5.9.2 are affected; the fix adds a per-write generation counter to the cache and raises WOLFSSL_CACHE_VERSION from 2 to 3, so a cache persisted by an older build is rejected by a fixed one.
INFO
Published Date :
Sept. 27, 2026, 9:16 a.m.
Last Modified :
Sept. 27, 2026, 9:16 a.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-94419
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | LOW | 50d2cd11-d01a-48ed-9441-5bfce9d63b27 | ||||
| CVSS 4.0 | LOW | [email protected] |
Solution
- Update wolfSSL to a version that includes the fix.
- Avoid builds with NO_SESSION_CACHE_REF defined.
- Use wolfSSL_get1_session() or wolfSSL_set_session() for session handling.
- Ensure WOLFSSL_CACHE_VERSION is updated to 3.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-94419.
| URL | Resource |
|---|---|
| https://github.com/wolfSSL/wolfssl/pull/11500 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-94419 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-94419
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-94419 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-94419 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Sep. 27, 2026
Action Type Old Value New Value Added Description Without NO_SESSION_CACHE_REF, wolfSSL_get_session() does not return a session object but a ClientSession reference of the form {row, index, hash(sessionID)} into the process-global SessionCache, and ClientSessionToSession() validates it against that hash alone. Because the TLS 1.2 session ID is chosen by the server and sent in clear, AddSessionToCache() matches any other server's session on the same ID and overwrites the client-side entry with that server's master secret, cipher suite and version, while the handle continues to resolve; nothing on the write path compares the peer, the application's server ID or the WOLFSSL_CTX. Resuming through the handle then produces an abbreviated handshake in which no Certificate message is sent, so neither chain verification nor wolfSSL_check_domain_name() runs, and the attacker is accepted as the original server for the whole of that connection. Affected builds are those leaving NO_SESSION_CACHE_REF, NO_SESSION_CACHE, NO_CLIENT_CACHE and TITAN_SESSION_CACHE all undefined, which includes a plain ./configure, --enable-opensslextra and --enable-opensslall; fifteen integration options define NO_SESSION_CACHE_REF and are therefore not affected, among them --enable-all, --enable-distro, --enable-curl, --enable-nginx, --enable-haproxy, --enable-stunnel, --enable-wpas and the rest of the OPENSSL_COMPATIBLE_DEFAULTS family, and --enable-leanpsk, --enable-leantls, --enable-lowresource and --enable-tinytls13 disable the cache outright. The application must use the legacy reference flow, wolfSSL_get_session() or SSL_get_session() followed by wolfSSL_set_session(); wolfSSL_get1_session() returns the session object itself and is not affected, nor are wolfSSL_SetServerID() lookups. Only TLS 1.2 and below and DTLS 1.2 and below are reachable, since TLS 1.3 and ticket resumption with an empty ServerHello session ID both use a client-chosen cache key. The poisoned entry lives in the process-global cache, so it crosses WOLFSSL_CTX boundaries and persists until the entry is evicted or the session times out, 500 seconds by default. Releases v5.3.0 through v5.9.2 are affected; the fix adds a per-write generation counter to the cache and raises WOLFSSL_CACHE_VERSION from 2 to 3, so a cache persisted by an older build is rejected by a fixed one. Added CVSS V4.0 AV:A/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-287 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/94xxx/CVE-2026-94419.json">CVE-2026-94419</a> Added Reference https://github.com/wolfSSL/wolfssl/pull/11500