---
cve: "CVE-2026-77696"
severity: "LOW"
cvss: 3.7
epss: "0.2%"
vendor: "OpenSSL"
kev: false
exploited: false
published: "2026-09-29 16:17:11"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-10-02T07:04:58+02:00"
---

# CVE-2026-77696

> 3.7 LOW · 🧪 PoC

## Beschreibung

Issue summary: SM2 signature generation uses non-constant-time arithmetic
on secret values, forming a timing side-channel.

Impact summary: An attacker able to measure SM2 signing times may learn
information about the per-signature secret nonce, which over many signatures
can, via a lattice / Hidden Number Problem attack, lead to recovery of the
private key.

CWE: CWE-208: Observable Timing Discrepancy

Description: SM2 signature generation computes the signature value using
variable-time BIGNUM operations on the secret nonce and the private key, so
the time taken to produce an SM2 signature depends on these secret values,
forming a timing side-channel.

Applications performing SM2 signature generation are affected on all
platforms.

FIPS Impact: no
SM2 is not a FIPS algorithm.

## CNA-Record (Kanon, cvelistV5)

- CNA: **openssl**
- State: PUBLISHED
- Stand: 2026-09-29 16:51:33

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **no**
  - Technical Impact: **partial**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Keine | good |
| A Verfügbarkeit | Keine | good |

## Schwachstellen-Klasse

- **CWE-208** — Observable Timing Discrepancy
  Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.

## Angriffsmuster (CAPEC)

- [CAPEC-462 — Cross-Domain Search Timing](https://capec.mitre.org/data/definitions/462.html) _(Severity: Medium)_
- [CAPEC-541 — Application Fingerprinting](https://capec.mitre.org/data/definitions/541.html) _(Severity: Low)_
- [CAPEC-580 — System Footprinting](https://capec.mitre.org/data/definitions/580.html) _(Severity: Low)_

## ATT&CK-Techniken

- [T1592.002 — Gather Victim Host Information: Software](https://attack.mitre.org/techniques/T1592/002/)
- [T1082 — System Information Discovery](https://attack.mitre.org/techniques/T1082/)

## Patch verfügbar (OSV)

- af1775b60dfa141a4ad762585052cabeb9f37e9e (Commit)
- c8bd5a57108599ac650bbae77fcabe3109dab2e8 (Commit)

## BSI-Hinweise (deutsch)

- [OpenSSL: Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-3638) — _BSI-Einstufung: hoch_
  Ein Angreifer kann mehrere Schwachstellen in OpenSSL ausnutzen, um Sicherheitsvorkehrungen zu umgehen, vertrauliche Informationen offenzulegen, Daten zu manipulieren und einen Denial-of-Service-Zustand zu verursachen.

## Referenzen

- <https://openssl-library.org/news/secadv/20260929.txt>
- <https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb>
- <https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9>
- <https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440>
- <https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-77696) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_