CVE-2026-77696 Timing Side-Channel in SM2 Signature Generation

What is CVE-2026-77696?

CVE-2026-77696 is a low-severity vulnerability in Openssl Openssl, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-208

Which versions are affected by CVE-2026-77696?

It affects 1 product.

Products include Openssl Openssl.

How do I fix CVE-2026-77696?

Apply the vendor's patch.

Is CVE-2026-77696 being exploited?

There is no known exploitation of CVE-2026-77696 in the wild and no public exploit code.

Other vulnerabilities in Openssl Openssl

• CVE-2009-3245 Null dereference in n/a Critical 10.0
• CVE-2006-3738 Memory corruption in n/a Critical 10.0
• CVE-2026-63073 Untrusted Sender DN Used as Format String in CMP Response Validation Critical 9.8
• CVE-2016-6309 Use after free in n/a Critical 9.8
• CVE-2016-0799 Integer overflow in n/a Critical 9.8

All Openssl Openssl vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2026-77696, AZL-105366, AZL-105465, AZL-105489, AZL-105519, AZL-105570 and 11 more.