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    CVE-2026-40356

    In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message.

    Published:Apr 28, 2026
    Last Modified:Apr 28, 2026
    EPS:Apr 28, 2026
    EPSS Score:0.00075
    CVSS Score:5.9

    Affected Products

    Vendor
    Mit
    Product
    Kerberos 5

    Exploits

    https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

    CVE-2026-40355 (CVSS 5.9) — In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_ac…
    CVE-2024-37370 (CVSS 7.5) — In MIT Kerberos 5 (aka krb5) before 1.21.3, an attacker can modify the plaintext Extra Count field of a confid…
    CVE-2024-37371 (CVSS 9.1) — In MIT Kerberos 5 (aka krb5) before 1.21.3, an attacker can cause invalid memory reads during GSS message toke…
    CVE-2024-26462 (CVSS 5.5) — Kerberos 5 (aka krb5) 1.21.2 contains a memory leak vulnerability in /krb5/src/kdc/ndr.c.…
    CVE-2024-26461 (CVSS 7.5) — Kerberos 5 (aka krb5) 1.21.2 contains a memory leak vulnerability in /krb5/src/lib/gssapi/krb5/k5sealv3.c.…
    CVE-2024-26458 (CVSS 5.3) — Kerberos 5 (aka krb5) 1.21.2 contains a memory leak in /krb5/src/lib/rpc/pmap_rmt.c.…
    CVE-2025-24528 (CVSS 7.1) — In MIT Kerberos 5 (aka krb5) before 1.22 (with incremental propagation), there is an integer overflow for a la…
    CVE-2023-39975 (CVSS 8.8) — kdc/do_tgs_req.c in MIT Kerberos 5 (aka krb5) 1.21 before 1.21.2 has a double free that is reachable if an aut…
    CVE-2023-36054 (CVSS 6.5) — lib/kadm5/kadm_rpc_xdr.c in MIT Kerberos 5 (aka krb5) before 1.20.2 and 1.21.x before 1.21.1 frees an uninitia…
    CVE-2022-42898 (CVSS 8.8) — PAC parsing in MIT Kerberos 5 (aka krb5) before 1.19.4 and 1.20.x before 1.20.1 has integer overflows that may…

    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