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    CVE-2026-40686

    In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.

    Published:Apr 30, 2026
    Last Modified:May 1, 2026
    EPS:Apr 30, 2026
    EPSS Score:0.00029
    CVSS Score:3.7

    Affected Products

    Vendor
    Exim
    Product
    Exim

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-125 Out-of-bounds Read

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-540 Overread Buffers

    Related CVEs

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    CVE-2026-48840 (CVSS 5.3) — Exim 4.88 before 4.99.4, in some proxy configurations, mishandles certain short payloads, leading to disclosur…
    CVE-2026-45185 (CVSS 9.8) — Exim before 4.99.3, in certain GnuTLS configurations, has a remotely reachable use-after-free in the BDAT body…
    CVE-2026-40684 (CVSS 5.9) — In Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance w…
    CVE-2026-40687 (CVSS 4.8) — In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can …
    CVE-2026-40685 (CVSS 6.5) — In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON operator…
    CVE-2025-67896 (CVSS 7) — Exim before 4.99.1, with certain non-default rate-limit configurations, allows a remote heap-based buffer over…
    CVE-2025-53881 (CVSS 6.9) — A UNIX Symbolic Link (Symlink) Following vulnerability in logrotate config in the exim package allowed privile…
    CVE-2025-30232 (CVSS 8.1) — A use-after-free in Exim 4.96 through 4.98.1 could allow users (with command-line access) to escalate privileg…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High