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VulnerabilityPublished Updated

CVE-2026-77696: Issue summary · SM2 signature generation uses non-constant-time arithmetic on secret values, forming a

Affects opensslSource GCVE Database

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Authoritative record:CVE-2026-77696· Low 3.7

Not known to be exploited · CVSS 3.7 Low · fixed in 3.1.0 : update openssl when convenient.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
3.7Low
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.13.7
EPSS
0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.1.0, 1.0.1f-1ubuntu2.27+esm17, 1.0.2g-1ubuntu4.20+esm19 +6
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
GitHubopenssl/opensslpkg:github/openssl/opensslOther threatsAffected
  • <3.1.0
Fixed in
  • 3.1.0
Ubuntu Pro 14.04 LTSopensslpkg:deb/ubuntu/openssl?arch=source&distro=esm-infra-legacy/trustyOther threatsAffected
  • <1.0.1f-1ubuntu2.27+esm17
Fixed in
  • 1.0.1f-1ubuntu2.27+esm17
Ubuntu Pro 16.04 LTSopensslpkg:deb/ubuntu/openssl?arch=source&distro=esm-infra-legacy/xenialOther threatsAffected
  • <1.0.2g-1ubuntu4.20+esm19
Fixed in
  • 1.0.2g-1ubuntu4.20+esm19
Ubuntu Pro 16.04 LTSedk2pkg:deb/ubuntu/edk2?arch=source&distro=esm-apps-legacy/xenialOther threatsAffected
  • 0~20150106.5c2d456b-2 – 0~20160408.ffea0a2c-2ubuntu0.2+esm4
8 affected builds
Fixed in–
Ubuntu Pro 16.04 LTSnodejspkg:deb/ubuntu/nodejs?arch=source&distro=esm-apps/xenialOther threatsAffected
  • 0.10.25~dfsg2-2ubuntu1 – 4.2.6~dfsg-1ubuntu4.2+esm3
12 affected builds
Fixed in–
Ubuntu Pro FIPS 16.04 LTSopensslpkg:deb/ubuntu/openssl?arch=source&distro=fips/xenialOther threatsAffected
  • 1.0.2g-1ubuntu4.fips.4.6 – 1.0.2g-1ubuntu4.fips.4.6~ppa3
7 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Official patches are available and should be applied by updating OpenSSL packages to the fixed versions provided by Ubuntu for the affected LTS releases. After updating, a system reboot is recommended to ensure all changes take effect. Users of Ubuntu Pro can obtain fixes through the Ubuntu Pro service. No additional mitigation actions are required beyond applying these updates.

Description

A timing side-channel vulnerability exists in OpenSSL's SM2 signature generation, where non-constant-time arithmetic on secret values may allow attackers to infer sensitive information. This issue affects multiple OpenSSL versions used in various Ubuntu LTS releases. The vulnerability has a low CVSS score of 3.7 and does not impact integrity or availability. Official patches are available from Ubuntu to address this issue.

References

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