CVE-2026-55958
TLS 1.3 handshake overflow in Renesas TSIP port can crash client.
Is CVE-2026-55958 being exploited?
Not confirmed. CVE-2026-55958 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.44% probability of exploitation in the next 30 days.
How severe is CVE-2026-55958?
CVE-2026-55958 is rated High with a CVSS score of 8.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-55958?
Yes. A fix has been recorded for CVE-2026-55958. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-55958 affect?
CVE-2026-55958 affects Renesas MCUs with TSIP hardware enabled using WolfSSL Renesas TSIP TLS port (TLS 1.3 client). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-55958?
Monitor TSIP TLS traffic; plan patch when available; consider disabling TSIP TLS port if feasible
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote DoS via oversized TLS 1.3 handshake; write past buffer causes heap corruption on Renesas TSIP TLS client.
Patch when possible
- affected>= 5.4.0 and <= 5.9.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.