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6.5 Medium

CVE-2026-70368 Stunnel: stack-based out-of-bounds read/write in stunnel s_vlog via oversized log message

Description

A stack-based out-of-bounds read vulnerability exists in the "s_vlog" function of stunnel, when handling oversized log messages via "vsnprintf". A remote attacker with network access to a stunnel service can send protocol inputs that trigger a log message longer than 1024 bytes, leading to an out-of-bounds stack read and a potential crash. In certain corner cases, the same vulnerability could be used to replace a series of trailing "\n" characters with "\0".

CVSS 3.1 detail

Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Exploitable remotely over the network, without an account and without any user action; the impact on data or service is limited.

Attack vector
Network
Attack complexity
Low
Privileges required
None
Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

Affected products and versions

Product Affected versions Fixed in
Red Hat Enterprise Linux 10 Versions not published
Red Hat Enterprise Linux 6 Versions not published
Red Hat Enterprise Linux 7 Versions not published
Red Hat Enterprise Linux 8 Versions not published
Red Hat Enterprise Linux 9 Versions not published
stunnel 5.68 5.68 → < 5.80 5.80

Other CVEs of Red Hat Enterprise Linux 10

The 1456 CVEs of Red Hat Enterprise Linux 10 →
CVE-2026-123876 Podman: containers-common: containers-common: default seccomp af_vsock/netlink_audit deny rules bypassable via 32-bit truncation 4.4 Medium CVE-2026-120749 Dbus: dbus-daemon: dbus-daemon aborts (reply_serial != 0) when a broadcast from the driver cannot be delivered to a monitored bus 6.2 Medium CVE-2026-123037 Ansible-core: user module generate_ssh_key follows a symlinked ~/.ssh enabling local privilege escalation (incomplete fix of cve-2024-9902) 6.7 Medium CVE-2026-123151 Gdb: gdb: stack buffer overflow in parse_tsv_definition via stale rs->buf tail Not rated
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