Out-of-Bounds Read in Openssl (CVE-2026-42771)
Summary
Vulnerability in Openssl (CVE-2026-42771). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
Issue summary: When the X509_VERIFY_PARAM_set1_email is called by an
application to validate a crafted e-mail address, such as during S/MIME
message validation, an out of bounds read can happen.
Impact summary: This out of bounds read will not directly exfiltrate
the data read to the attacker so the most likely result is a crash and
a Denial of Service.
An internal helper function called from X509_VERIFY_PARAM_[set|add]_email()
used a wrong length when validating the local part of an email address.
This could cause the 64 octet limit on the local part of an email address
to be not enforced, or cause an out of bound read and potentially a crash.
The bug is reachable via S-MIME validation with a crafted From: address
supplied in an email message that can potentially cause a crash.
No FIPS modules are affected by this issue as the affected code is outside
the OpenSSL FIPS module boundary.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-42771 has been found in Openssl.
Risk of unauthorized operations or information disclosure. CVSS score: 6.2/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Openssl CVE-2026-42771" on the vendor's site.
CVE-2026-42771 (Openssl) — CWE-125 / CVSS v3 6.2
Attack vector: local / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds read (CWE-125) exists in Openssl.
Check the vendor advisory for the affected versions of Openssl.
Severity: Medium (CVSS 6.2/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Openssl' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Openssl' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Opensslを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-42771
- Ubuntu UBUNTU-CVE-2026-42771 nodejs
References
- advisory nvd.nist.gov
- advisory openssl-library.org
- advisory github.com
- patch github.com
- web github.com
- web github.com