CVE Watch4 ago 2026

CVE-2021-47555

In the Linux kernel, the following vulnerability has been resolved: net: vlan: fix underflow for the real_dev refcnt Inject error before d

CVSS

7.8

Alto

EPSS

0.2%

p13

KEV

—

Exploit Today

0-100

Publicado: 24 may 2024 · Última mod.: 4 ago 2026 · CWE-191

EPSS · 30d

0.2%EPSS · 30 días0.2%

2026-07-232026-08-20

Descripción técnica

In the Linux kernel, the following vulnerability has been resolved: net: vlan: fix underflow for the real_dev refcnt Inject error before dev_hold(real_dev) in register_vlan_dev(), and execute the following testcase: ip link add dev dummy1 type dummy ip link add name dummy1.100 link dummy1 type vlan id 100 ip link del dev dummy1 When the dummy netdevice is removed, we will get a WARNING as following: ======================================================================= refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 2 PID: 0 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 and an endless loop of: ======================================================================= unregister_netdevice: waiting for dummy1 to become free. Usage count = -1073741824 That is because dev_put(real_dev) in vlan_dev_free() be called without dev_hold(real_dev) in register_vlan_dev(). It makes the refcnt of real_dev underflow. Move the dev_hold(real_dev) to vlan_dev_init() which is the call-back of ndo_init(). That makes dev_hold() and dev_put() for vlan's real_dev symmetrical.

Referencias oficiales

CVEs relacionados

CVECVSSEPSSKEVRExplotTítuloVis.

CVE-2026-169247.5 ALT

—

——0IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a remote attacker to cause a denial of service due to an improper calculation of a memory offset during IPsec decapsulation.1d CVE-2026-580877.8 ALT

6.2%

——2The GETALL and SETALL commands in semctl(2) recorded the number of semaphores in the target set, dropped the lock protecting the set, allocated a buffer sized for that count, and reacquired the lock. A sequence-number check was used to verify that the set had not been replaced in the interim, but the sequence number wraps after 0x8000 create/destroy cycles. By rapidly destroying and recreating semaphore sets at the same index, another process can cause the sequence number to wrap, allowing a set with a different number of semaphores to pass validation. The subsequent copy then reads or writes past the end of the allocated buffer. An unprivileged local user can trigger out-of-bounds reads and writes on kernel heap memory, potentially leading to privilege escalation.2d CVE-2026-622894.3 MED

32.9%

——10libheif is a HEIF and AVIF file format decoder and encoder. In 1.23.0 and earlier, a crafted HEIF or AVIF file containing a clean aperture box can reduce an image dimension to zero and crash or corrupt tiling results when heif_image_handle_get_image_tiling(handle, 1, &tiling) is called. ImageItem::get_heif_image_tiling() returns already transformed dimensions, and process_image_transformations_on_tiling() applies the clean aperture transformation again. The second application passes zero to Box_clap::left_rounded(0), where image_width minus one underflows and constructs Fraction(0xFFFFFFFF, 2). Debug builds reach an assertion and abort, while release builds can return a corrupt crop and zero-width tiling result. The affected implementation spans libheif/image-items/image_item.cc, libheif/context.cc, and libheif/box.cc. This issue is fixed in version 1.23.1.2d CVE-2026-456987.5 ALT

19.6%

——6Netatalk is a Free and Open Source file server suite for Unix-like operating systems. In versions 3.1.19 through 4.4.2, a stack-based buffer overflow exists in the deletedir() function of Netatalk's afpd daemon due to an integer underflow in the calculation of the remaining buffer size used for path construction. deletedir() is a utility function called when a file operation crosses a device boundary inside an AFP shared volume, which the standard library's renameat() cannot handle. The function attempts to prevent buffer overflows by tracking available space in a size_t remain variable. However, the arithmetic used to compute remain results in an unsigned integer underflow, causing the variable to become SIZE_MAX. Because of this, the subsequent boundary check always evaluates as safe, allowing an unbounded strcpy() operation to copy attacker-controlled filenames into a nearly full stack buffer. Version 4.4.3 patches the issue.4d CVE-2026-456997.5 ALT

26.6%

——8Netatalk is a Free and Open Source file server suite for Unix-like operating systems. In versions 3.1.19 through 4.4.2, a stack-based buffer overflow exists in the copydir() function of Netatalk's afpd daemon due to an integer underflow in the calculation of the remaining buffer size used for path construction. copydir() is a utility function called when a file operation crosses a device boundary inside an AFP shared volume, which the standard library's renameat() cannot handle. The function attempts to track available buffer space using srem and drem for source and destination paths. Incorrect arithmetic causes both srem and drem to underflow to SIZE_MAX. Consequently, boundary checks against strlen(de->d_name) always pass, allowing strcpy() to append filenames into nearly full stack buffers. Version 4.4.3 patches the issue. As a workaround, configure each AFP shared volume to be structured as a single file system, in other words no subdirectory of a shared volume should be a mount point for a different file system.4d CVE-2026-492825.1 MED

3.2%

——1Capstone is a disassembly framework. Prior to version 6.0.0-Alpha9, Capstone's public `cs_insn_name()` API forwards caller-supplied instruction IDs directly to the selected architecture backend. Most backends validate the ID before indexing instruction-name tables, but the M68K and RISCV backends have missing or incomplete bounds checks. On a Capstone handle opened for M68K or RISCV, a caller-controlled invalid instruction ID can trigger an out-of-bounds read and crash the process. The demonstrated impact is availability loss in applications or bindings that expose instruction-name lookup to untrusted IDs. No code execution or data disclosure was demonstrated. Version 6.0.0-Alpha9 patches the issue.4d