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CVE-2026-42771

Possible Out of Bounds Read in X509_VERIFY_PARAM_set1_email()

Medium6.2EPSS 0.22%
Published
Updated
Reserved
Assigned by
openssl

Description

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.

Timeline

  1. ID reserved

    By openssl

  2. · 41 days later

    Published

  3. · 1 day later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-42771, by who scored it
Scored byCVSSScoreVector
CISA-ADPADP (enrichment)3.1Medium6.2CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Analyzed3.1Medium6.2CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.22% · top 88% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.2.

Weakness

Affected products

References (2)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .