CVE-2026-40955
CVE-2026-40955 is an integer underflow vulnerability in the traffic parsing function of Secure Access clients prior to 14.55. Attackers with
CVSS
3.7
Low
EPSS
0.2%
p10
KEV
—
Exploit Today
3
0-100
Published: Jul 15, 2026 · Last modified: Jul 16, 2026 · CWE-191
0.2%EPSS · 30 days0.2%
2026-07-162026-07-17
CVE-2026-40955 is an integer underflow vulnerability in the traffic parsing function of Secure Access clients prior to 14.55. Attackers with intimate knowledge of and total control over the tunnel protocol can create a non-persistent DoS against their client.
CVECVSSEPSSKEVRExploitTitleMod.
CVE-2026-250757.5 HIG59.3%
——18strongSwan versions 4.5.0 prior to 6.0.5 contain an integer underflow vulnerability in the EAP-TTLS AVP parser that allows unauthenticated remote attackers to cause a denial of service by sending crafted AVP data with invalid length fields during IKEv2 authentication. Attackers can exploit the failure to validate AVP length fields before subtraction to trigger excessive memory allocation or NULL pointer dereference, crashing the charon IKE daemon.4dCVE-2026-338457.5 HIG52.7%
——16A flaw in GnuTLS DTLS handshake parsing allows malformed fragments with zero length and non-zero offset, leading to an integer underflow during reassembly and resulting in an out-of-bounds read. This issue is remotely exploitable and may cause information disclosure or denial of service.3dCVE-2026-491817.5 HIG51.0%
——15Integer underflow (wrap or wraparound) in Windows DHCP Client allows an unauthorized attacker to elevate privileges over a network.2dCVE-2026-531769.8 CRI50.5%
——15In the Linux kernel, the following vulnerability has been resolved:
IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN
In drivers/infiniband/ulp/isert/ib_isert.c, isert_login_recv_done()
computes the login request payload length as wc->byte_len minus
ISER_HEADERS_LEN with no lower bound, and login_req_len is a signed int.
A remote iSER initiator can post a login Send work request carrying
fewer than ISER_HEADERS_LEN (76) bytes, so the subtraction underflows
and login_req_len becomes negative.
isert_rx_login_req() then reads that negative length back into a signed
int, takes size = min(rx_buflen, MAX_KEY_VALUE_PAIRS), and because the
min() is signed it keeps the negative value; the value is then passed as
the memcpy() length and sign-extended to a multi-gigabyte size_t. The
copy into the 8192-byte login->req_buf runs far out of bounds and
faults, crashing the target node. The login phase precedes iSCSI
authentication, so no credentials are required to reach this path.
Reject any login PDU shorter than ISER_HEADERS_LEN before the
subtraction, mirroring the existing early return on a failed work
completion, so login_req_len can never go negative. The upper bound was
already safe: a posted login buffer cannot deliver more than
ISER_RX_PAYLOAD_SIZE, so the difference stays at or below
MAX_KEY_VALUE_PAIRS and the existing min() clamps it; only the missing
lower bound needs to be added.3dCVE-2026-554906.5 MED48.4%
——15OpenWrt is a Linux operating system targeting embedded devices. Before v25.12.5, an integer underflow in handle_send_a() of the Emergency Access Daemon allows any unauthenticated attacker on the local network to crash the daemon by sending a single crafted UDP packet. The message length underflows before a bounds check and is then passed to memcpy as a very large size. This issue is fixed v25.12.5.8dCVE-2025-49487.5 HIG47.3%
——14A flaw was found in the soup_multipart_new_from_message() function of the libsoup HTTP library, which is commonly used by GNOME and other applications to handle web communications. The issue occurs when the library processes specially crafted multipart messages. Due to improper validation, an internal calculation can go wrong, leading to an integer underflow. This can cause the program to access invalid memory and crash. As a result, any application or server using libsoup could be forced to exit unexpectedly, creating a denial-of-service (DoS) risk.18d