CVE-2026-5295:wolfssl: Stack-based buffer overflow
A historical CVE, retraced through the questions Lachesis asks of vulnerable code.
An oversized identifier from a PKCS7 message was copied into a fixed stack buffer without a matching size check.
That is the shape of the failure. The rest of this case file follows the evidence behind it.
What was known.
What Lachesis established.
Known before Lachesis ran
The CVE and vulnerable release were selected from public history. We are not claiming novel discovery.
- CVE
- CVE-2026-5295
- Vulnerable target
- v5.9.0-stable (affected: <= 5.9.0) · vulnerable
- Prior knowledge
- CVE-2026-5295 · v5.9.0-stable (affected: <= 5.9.0) is vulnerable
Independent re-detection
The experiment graph was built around the vulnerable wc_PKCS7_DecryptOri() (release v5.9.0-stable, wolfcrypt/src/pkcs7.c), rather than starting from arbitrary wolfSSL source. We did not point the tool at the CVE. Enumeration ran over the whole candidate registry (every family); the memory.copy sink came out of it on its own, and Lachesis carried the attacker-controlled OID length into the fixed-size buffer copy. Every field under sast_output is the enumerator's own emission; the mechanism under adjudication is my reading of the source and fix.
- Seeded inputs
- None
- Run timestamp
- 2026-08-24T12:06:09Z
- Evidence artifact
- ~/.lachesis/graphs/wolfssl_decryptori.kuzu
The commands and outputs below come from this recorded Lachesis run.
What Lachesis reconstructed.
One historical repository. Four captured queries. A complete source-to-sink argument.
Lachesis follows the same evidence path through unfamiliar repositories.
Here is how the path becomes visible.
These are the recorded questions Lachesis asked of the historical vulnerable code, followed by the raw result and source location each query returned.
Captured runThis is a real replay of Lachesis over the graph we built for this case. Every command below was run against the wolfssl DecryptOri graph and every result is the output captured on that drive. We did not name a family. The hunt listed the whole taxonomy first and the memory copy sink came out of it. No PKCS7 message was seeded; the graph was built from the source alone and the finding was rediscovered from graph structure, so the mode is independent-redetection.
Load the graph and list every bug family
First we load the graph and ask the tool to list every bug family, with nothing chosen ahead of time. It reports all 8 domains and 31 sink constructors and says the census is complete for what the graph can observe. The memory copy family is one row among all of them.
[lachesis-mcp] loaded the graph; overlay: 0 derived edges; dataflow tier: on demand, per cone
CANDIDATE_CENSUS
move: candidate_census
taxonomy (8):
domain=lifecycle title=Resource lifecycle enumerable=True
domain=memory title=Memory safety enumerable=True
domain=injection title=Injection enumerable=True
domain=navigation title=Request forgery & redirection enumerable=True
domain=object-integrity title=Object integrity enumerable=True
domain=filesystem title=Filesystem enumerable=True
domain=crypto-config title=Cryptography & transport config enumerable=True
domain=resource title=Resource exhaustion enumerable=True
constructors (31): complete_for_observable_graph=True
applied: True
role_nodes: {sink: 2}A small line with a large consequence.
No bounds check compares the copy size with the destination buffer size.
XMEMCPY(oriOID, pkiMsg + *idx, (word32)oriOIDSz);
// if (oriOIDSz <= 0 || (word32)oriOIDSz > MAX_OID_SZ) return ASN_PARSE_E; (fixed in 5.9.1)
The original record.
Read the historical advisory and vulnerability record behind this reconstruction.