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CVE archive

April 2021

Browse CVE records published in April 2021, with severity, affected products, CWE, KEV, and source-backed vulnerability context.

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Showing 50 of 2026 matching CVEs · Page 2 of 41.

Unknown · CVSS Not scored

CVE-2021-47190: perf bpf: Avoid memory leak from perf_env__insert_btf()

In the Linux kernel, the following vulnerability has been resolved: perf bpf: Avoid memory leak from perf_env__insert_btf() perf_env__insert_btf() doesn't insert if a duplicate BTF id is encountered and this causes a memory leak. Modify the function to return a success/error value and then free the memory if insertion didn't happen. v2. Adds a return -1 when the insertion error occurs in perf_env__fetch_btf. This doesn't affect anything as the result is never checked.

Published Apr 10, 2024 · Updated May 11, 2026

Medium · CVSS 6.3

CVE-2021-47189: btrfs: fix memory ordering between normal and ordered work functions

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix memory ordering between normal and ordered work functions Ordered work functions aren't guaranteed to be handled by the same thread which executed the normal work functions. The only way execution between normal/ordered functions is synchronized is via the WORK_DONE_BIT, unfortunately the used bitops don't guarantee any ordering whatsoever. This manifested as seemingly inexplicable crashes on ARM64, where async_chunk::inode is seen as non-null in async_cow_submit which causes submit_compressed_extents to be called and crash occurs because async_chunk::inode suddenly became NULL. The call trace was similar to: pc : submit_compressed_extents+0x38/0x3d0 lr : async_cow_submit+0x50/0xd0 sp : ffff800015d4bc20 <registers omitted for brevity> Call trace: submit_compressed_extents+0x38/0x3d0 async_cow_submit+0x50/0xd0 run_ordered_work+0xc8/0x280 btrfs_work_helper+0x98/0x250 process_one_work+0x1f0/0x4ac worker_thread+0x188/0x504 kthread+0x110/0x114 ret_from_fork+0x10/0x18 Fix this by adding respective barrier calls which ensure that all accesses preceding setting of WORK_DONE_BIT are strictly ordered before setting the flag. At the same time add a read barrier after reading of WORK_DONE_BIT in run_ordered_work which ensures all subsequent loads would be strictly ordered after reading the bit. This in turn ensures are all accesses before WORK_DONE_BIT are going to be strictly ordered before any access that can occur in ordered_func.

Published Apr 10, 2024 · Updated May 11, 2026

Unknown · CVSS Not scored

CVE-2021-47187: arm64: dts: qcom: msm8998: Fix CPU/L2 idle state latency and residency

In the Linux kernel, the following vulnerability has been resolved: arm64: dts: qcom: msm8998: Fix CPU/L2 idle state latency and residency The entry/exit latency and minimum residency in state for the idle states of MSM8998 were ..bad: first of all, for all of them the timings were written for CPU sleep but the min-residency-us param was miscalculated (supposedly, while porting this from downstream); Then, the power collapse states are setting PC on both the CPU cluster *and* the L2 cache, which have different timings: in the specific case of L2 the times are higher so these ones should be taken into account instead of the CPU ones. This parameter misconfiguration was not giving particular issues because on MSM8998 there was no CPU scaling at all, so cluster/L2 power collapse was rarely (if ever) hit. When CPU scaling is enabled, though, the wrong timings will produce SoC unstability shown to the user as random, apparently error-less, sudden reboots and/or lockups. This set of parameters are stabilizing the SoC when CPU scaling is ON and when power collapse is frequently hit.

Published Apr 10, 2024 · Updated May 11, 2026

Unknown · CVSS Not scored

CVE-2021-47186: tipc: check for null after calling kmemdup

In the Linux kernel, the following vulnerability has been resolved: tipc: check for null after calling kmemdup kmemdup can return a null pointer so need to check for it, otherwise the null key will be dereferenced later in tipc_crypto_key_xmit as can be seen in the trace [1]. [1] https://syzkaller.appspot.com/bug?id=bca180abb29567b189efdbdb34cbf7ba851c2a58

Published Apr 10, 2024 · Updated May 11, 2026

Medium · CVSS 4.4

CVE-2021-47185: tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc

In the Linux kernel, the following vulnerability has been resolved: tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc When running ltp testcase(ltp/testcases/kernel/pty/pty04.c) with arm64, there is a soft lockup, which look like this one: Workqueue: events_unbound flush_to_ldisc Call trace: dump_backtrace+0x0/0x1ec show_stack+0x24/0x30 dump_stack+0xd0/0x128 panic+0x15c/0x374 watchdog_timer_fn+0x2b8/0x304 __run_hrtimer+0x88/0x2c0 __hrtimer_run_queues+0xa4/0x120 hrtimer_interrupt+0xfc/0x270 arch_timer_handler_phys+0x40/0x50 handle_percpu_devid_irq+0x94/0x220 __handle_domain_irq+0x88/0xf0 gic_handle_irq+0x84/0xfc el1_irq+0xc8/0x180 slip_unesc+0x80/0x214 [slip] tty_ldisc_receive_buf+0x64/0x80 tty_port_default_receive_buf+0x50/0x90 flush_to_ldisc+0xbc/0x110 process_one_work+0x1d4/0x4b0 worker_thread+0x180/0x430 kthread+0x11c/0x120 In the testcase pty04, The first process call the write syscall to send data to the pty master. At the same time, the workqueue will do the flush_to_ldisc to pop data in a loop until there is no more data left. When the sender and workqueue running in different core, the sender sends data fastly in full time which will result in workqueue doing work in loop for a long time and occuring softlockup in flush_to_ldisc with kernel configured without preempt. So I add need_resched check and cond_resched in the flush_to_ldisc loop to avoid it.

Published Apr 10, 2024 · Updated May 11, 2026

Unknown · CVSS Not scored

CVE-2021-47184: i40e: Fix NULL ptr dereference on VSI filter sync

In the Linux kernel, the following vulnerability has been resolved: i40e: Fix NULL ptr dereference on VSI filter sync Remove the reason of null pointer dereference in sync VSI filters. Added new I40E_VSI_RELEASING flag to signalize deleting and releasing of VSI resources to sync this thread with sync filters subtask. Without this patch it is possible to start update the VSI filter list after VSI is removed, that's causing a kernel oops.

Published Apr 10, 2024 · Updated May 11, 2026

Unknown · CVSS Not scored

CVE-2021-47183: scsi: lpfc: Fix link down processing to address NULL pointer dereference

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Fix link down processing to address NULL pointer dereference If an FC link down transition while PLOGIs are outstanding to fabric well known addresses, outstanding ABTS requests may result in a NULL pointer dereference. Driver unload requests may hang with repeated "2878" log messages. The Link down processing results in ABTS requests for outstanding ELS requests. The Abort WQEs are sent for the ELSs before the driver had set the link state to down. Thus the driver is sending the Abort with the expectation that an ABTS will be sent on the wire. The Abort request is stalled waiting for the link to come up. In some conditions the driver may auto-complete the ELSs thus if the link does come up, the Abort completions may reference an invalid structure. Fix by ensuring that Abort set the flag to avoid link traffic if issued due to conditions where the link failed.

Published Apr 10, 2024 · Updated May 11, 2026

Unknown · CVSS Not scored

CVE-2021-47182: scsi: core: Fix scsi_mode_sense() buffer length handling

In the Linux kernel, the following vulnerability has been resolved: scsi: core: Fix scsi_mode_sense() buffer length handling Several problems exist with scsi_mode_sense() buffer length handling: 1) The allocation length field of the MODE SENSE(10) command is 16-bits, occupying bytes 7 and 8 of the CDB. With this command, access to mode pages larger than 255 bytes is thus possible. However, the CDB allocation length field is set by assigning len to byte 8 only, thus truncating buffer length larger than 255. 2) If scsi_mode_sense() is called with len smaller than 8 with sdev->use_10_for_ms set, or smaller than 4 otherwise, the buffer length is increased to 8 and 4 respectively, and the buffer is zero filled with these increased values, thus corrupting the memory following the buffer. Fix these 2 problems by using put_unaligned_be16() to set the allocation length field of MODE SENSE(10) CDB and by returning an error when len is too small. Furthermore, if len is larger than 255B, always try MODE SENSE(10) first, even if the device driver did not set sdev->use_10_for_ms. In case of invalid opcode error for MODE SENSE(10), access to mode pages larger than 255 bytes are not retried using MODE SENSE(6). To avoid buffer length overflows for the MODE_SENSE(10) case, check that len is smaller than 65535 bytes. While at it, also fix the folowing: * Use get_unaligned_be16() to retrieve the mode data length and block descriptor length fields of the mode sense reply header instead of using an open coded calculation. * Fix the kdoc dbd argument explanation: the DBD bit stands for Disable Block Descriptor, which is the opposite of what the dbd argument description was.

Published Apr 10, 2024 · Updated May 11, 2026

Medium · CVSS 6.5

CVE-2021-47960: A files or directories accessible to external parties vulnerability in Synology SSL VPN Client before 1.4.5...

A files or directories accessible to external parties vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access files within the installation directory via a local HTTP server bound to the loopback interface. By leveraging user interaction with a crafted web page, attackers may retrieve sensitive files such as configuration files, certificates, and logs, leading to information disclosure.

Published Apr 10, 2026 · Updated Apr 10, 2026

High · CVSS 8.1

CVE-2021-47961: A plaintext storage of a password vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote...

A plaintext storage of a password vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access or influence the user's PIN code due to insecure storage. This may lead to unauthorized VPN configuration and potential interception of subsequent VPN traffic when combined with user interaction.

Published Apr 10, 2026 · Updated Apr 10, 2026

Critical · CVSS 9.8

CVE-2021-4455: Wordpress Plugin Smart Product Review <= 1.0.4 - Unauthenticated Arbitrary File Upload

The Wordpress Plugin Smart Product Review plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in all versions up to, and including, 1.0.4. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.

Published Apr 19, 2025 · Updated Apr 8, 2026

Medium · CVSS 6.3

CVE-2021-29449: Multiple Privilege Escalation Vulnerabilities Pihole

Pi-hole is a Linux network-level advertisement and Internet tracker blocking application. Multiple privilege escalation vulnerabilities were discovered in version 5.2.4 of Pi-hole core. See the referenced GitHub security advisory for details.

Published Apr 14, 2021 · Updated Apr 6, 2026

Critical · CVSS 9.3

CVE-2021-4477: Hirschmann HiLCOS OpenBAT BAT450 IPv6 IPsec Firewall Bypass

Hirschmann HiLCOS OpenBAT and BAT450 products contain a firewall bypass vulnerability in IPv6 IPsec deployments that allows traffic from VPN connections to bypass configured firewall rules. Attackers can exploit this vulnerability by establishing IPv6 IPsec connections (IKEv1 or IKEv2) while simultaneously using an IPv6 Internet connection to circumvent firewall policy enforcement.

Published Apr 3, 2026 · Updated Apr 6, 2026

Medium · CVSS 4

CVE-2021-3448: A flaw was found in dnsmasq in versions before 2.85.

A flaw was found in dnsmasq in versions before 2.85. When configured to use a specific server for a given network interface, dnsmasq uses a fixed port while forwarding queries. An attacker on the network, able to find the outgoing port used by dnsmasq, only needs to guess the random transmission ID to forge a reply and get it accepted by dnsmasq. This flaw makes a DNS Cache Poisoning attack much easier. The highest threat from this vulnerability is to data integrity.

Published Apr 8, 2021 · Updated Dec 3, 2025

Unknown · CVSS Not scored

CVE-2021-3652: A flaw was found in 389-ds-base.

A flaw was found in 389-ds-base. If an asterisk is imported as password hashes, either accidentally or maliciously, then instead of being inactive, any password will successfully match during authentication. This flaw allows an attacker to successfully authenticate as a user whose password was disabled.

Published Apr 18, 2022 · Updated Nov 3, 2025

High · CVSS 7 · CISA KEV

CVE-2021-1782: A race condition was addressed with improved locking.

A race condition was addressed with improved locking. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. A malicious application may be able to elevate privileges. Apple is aware of a report that this issue may have been actively exploited..

Published Apr 2, 2021 · Updated Oct 21, 2025

High · CVSS 8.8 · CISA KEV

CVE-2021-1789: A type confusion issue was addressed with improved state handling.

A type confusion issue was addressed with improved state handling. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, tvOS 14.4, watchOS 7.3, iOS 14.4 and iPadOS 14.4, Safari 14.0.3. Processing maliciously crafted web content may lead to arbitrary code execution.

Published Apr 2, 2021 · Updated Oct 21, 2025

Critical · CVSS 9.8 · CISA KEV

CVE-2021-1870: A logic issue was addressed with improved restrictions.

A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

Published Apr 2, 2021 · Updated Oct 21, 2025

Critical · CVSS 9.8 · CISA KEV

CVE-2021-1871: A logic issue was addressed with improved restrictions.

A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

Published Apr 2, 2021 · Updated Oct 21, 2025

Medium · CVSS 6.1 · CISA KEV

CVE-2021-1879: This issue was addressed by improved management of object lifetimes.

This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited..

Published Apr 2, 2021 · Updated Oct 21, 2025

High · CVSS 8.8 · CISA KEV

CVE-2021-3493: The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces...

The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.

Published Apr 17, 2021 · Updated Oct 21, 2025