-----BEGIN SECURITY ADVISORY-----

Title: Multiple Integer Overflows in U-Boot Filesystem Handling Author: Timo Preißl <t.preissl () proton me> Date: 2026-02-11 CVEs: CVE-2025-70290, CVE-2025-70291, CVE-2025-70292, CVE-2025-70293 Affected: Denx U-Boot <= v2026.01-rc4 Fixed in: v2026.04-rc1 (commit adccdb2)

== Overview ==

Multiple integer overflow vulnerabilities were discovered in the U-Boot bootloader's filesystem handling code and command-line interface. These flaws can lead to heap memory under-allocation followed by heap-based buffer overflows, potentially allowing Arbitrary Code Execution (ACE) in the pre-boot environment.

== Vulnerability Details ==

--- CVE-2025-70290: ZFS Metadata Integer Overflow ---

Component: fs/zfs/zfs.c, function zfsnvlistlookupnvlist Impact: A crafted ZFS filesystem image with malformed on-disk metadata can trigger an integer overflow during the size calculation passed to calloc(), resulting in an undersized allocation and subsequent out-of-bounds memory access. Fix: Validation of allocation size using builtinaddoverflow.

--- CVE-2025-70291: Heap Buffer Overflow in domv Command ---

Component: fs/fs.c, function domv Impact: Missing length checks in the directory move command allow an integer overflow during string length addition. An attacker with U-Boot shell access can trigger an under-allocation, resulting in a heap buffer overflow via strcpy(). Fix: Safe addition of string lengths using compiler intrinsics.

--- CVE-2025-70292: SquashFS Integer Overflow ---

Component: fs/squashfs/sqfs.c, function sqfsconcattokens Impact: Manipulated token lists trigger an overflow in sqfsgettokenslength(), causing heap under-allocation subsequently overflown by strcpy(). Fix: Validation of total token length before allocation.

--- CVE-2025-70293: EXT4 Block Group Descriptor Table Integer Overflow ---

Component: fs/ext4/ext4write.c, function ext4fsgetbgdtable Impact: An integer overflow in the block group descriptor table size calculation results in an undersized buffer being passed to memcpy(), causing memory corruption. Fix: Guarded multiplication of block group count and descriptor size.

== Patch ==

All issues are fixed in the U-Boot master branch.

Commit: adccdb2f605a6e8e046712398712398123 "fix integer overflows in filesystem code"

https://source.denx.de/u-boot/u-boot/-/commit/adccdb2

== Timeline ==

Patch series submitted to upstream mailing list: https://lore.kernel.org/u-boot/20251231100831.119142-1-t.preissl () proton me/T/

Fix merged: v2026.04-rc1 -----END SECURITY ADVISORY-----

An issue was discovered in Denx U-Boot before 2026.04. An integer overflow vulnerability in the ZFS filesystem support can be triggered by malformed on-disk metadata. The issue may result in incorrect memory allocation followed by out-of-bounds memory access, potentially leading to a crash or arbitrary code execution during the boot process.

U-Boot before 2026.07-rc2 contains a buffer overflow vulnerability in nfsreadlinkreply() (net/nfs-common.c) when CONFIGCMDNFS is enabled, allowing a malicious or compromised NFS server to overflow the 2048-byte nfspathbuff buffer by returning multiple relative symlink targets that are appended without cumulative length validation. Attackers can send two or more READLINK responses containing relative symlink targets of approximately 1100 bytes each to corrupt adjacent BSS variables including nfsserverip, nfsservermountport, nfsserverport, nfsourport, nfsstate, and rpcid, potentially achieving memory corruption and control over the NFS client state machine.

U-Boot through 2026.04-rc3 contains an integer underflow vulnerability in the tcprxstatemachine() function (net/tcp.c) that allows a network-adjacent attacker to crash the bootloader by sending a malformed TCP SYN+ACK packet with a manipulated data offset field causing payloadlen to become negative. When the TCPSYNSENT handler calls tcprxuserdata() without invoking tcpseginwnd() validation, the negative payloadlen is implicitly converted to a large unsigned integer (e.g., 0xFFFFFFD8) and passed to memcpy() in storeblock(), causing an immediate crash that prevents device boot and may enable memory corruption when CONFIGLMB is disabled.

U-Boot through 2026.04-rc3 contains an out-of-bounds read vulnerability in tcprxstatemachine() (net/tcp.c) when CONFIGPROTTCP is enabled, allowing remote attackers to read beyond TCP segment boundaries by crafting a malicious packet with a mismatched IP total length and TCP data offset field. Attackers can send a packet with an IP total length of 40 bytes and a TCP data offset claiming 60 bytes of header to cause tcpparseoptions() to read 40 bytes past the end of the TCP segment, potentially corrupting connection state variables such as rmtwinscale and rmttimestamp to disrupt TCP window calculations.

Das U-Boot before 2026.04 allows FIT (Flat Image Tree) signature verification bypass because hashed-nodes is omitted from a hash.

In Das U-Boot through 2020.01, a double free has been found in the cmd/gpt.c dorenamegptparts() function. Double freeing may result in a write-what-where condition, allowing an attacker to execute arbitrary code. NOTE: this vulnerablity was introduced when attempting to fix a memory leak identified by static analysis.

Integer overflows in memory allocation in Das U-Boot before 2025.01-rc1 occur for a crafted squashfs filesystem via sbrk, via request2size, or because ptrdifft is mishandled on x8664.

An integer overflow in ext4fsreadsymlink in Das U-Boot before 2025.01-rc1 occurs for zalloc (adding one to an le32 variable) via a crafted ext4 filesystem with an inode size of 0xffffffff, resulting in a malloc of zero and resultant memory overwrite.

In Das U-Boot through 2022.07-rc5, an integer signedness error and resultant stack-based buffer overflow in the "i2c md" command enables the corruption of the return address pointer of the doi2cmd function.

Das U-Boot 2022.01 has a Buffer Overflow, a different issue than CVE-2022-30552.

Das U-Boot 2022.01 has a Buffer Overflow.

There exists an unchecked length field in UBoot. The U-Boot DFU implementation does not bound the length field in USB DFU download setup packets, and it does not verify that the transfer direction corresponds to the specified command. Consequently, if a physical attacker crafts a USB DFU download setup packet with a wLength greater than 4096 bytes, they can write beyond the heap-allocated request buffer.

Das U-Boot through 2020.01 allows attackers to bypass verified boot restrictions and subsequently boot arbitrary images by providing a crafted FIT image to a system configured to boot the default configuration.

An issue was discovered in Das U-Boot through 2019.07. There is a stack-based buffer overflow in this nfshandler reply helper function: nfslookupreply.

An issue was discovered in Das U-Boot through 2019.07. There is a stack-based buffer overflow in this nfshandler reply helper function: nfsreadlinkreply.

An issue was discovered in Das U-Boot through 2019.07. There is a read of out-of-bounds data at nfsreadreply.

An issue was discovered in Das U-Boot through 2019.07. There is an unbounded memcpy when parsing a UDP packet due to a netprocessreceivedpacket integer underflow during an udppackethandler call.

An issue was discovered in Das U-Boot through 2019.07. There is an unbounded memcpy with a failed length check at nfsreadreply when calling storeblock in the NFSv3 case.

An issue was discovered in Das U-Boot through 2019.07. There is a stack-based buffer overflow in this nfshandler reply helper function: rpclookupreply.

An issue was discovered in Das U-Boot through 2019.07. There is a stack-based buffer overflow in this nfshandler reply helper function: nfsumountallreply.

An issue was discovered in Das U-Boot through 2019.07. There is a stack-based buffer overflow in this nfshandler reply helper function: nfsmountreply.

In Das U-Boot versions 2016.11-rc1 through 2019.07-rc4, an underflow can cause memcpy() to overwrite a very large amount of data (including the whole stack) while reading a crafted ext4 filesystem.

Das U-Boot versions 2016.09 through 2019.07-rc4 can memset() too much data while reading a crafted ext4 filesystem, which results in a stack buffer overflow and likely code execution.

An issue was discovered in Das U-Boot through 2019.07. There is an unbounded memcpy with a failed length check at nfslookupreply.

An issue was discovered in Das U-Boot through 2019.07. There is an unbounded memcpy with a failed length check at nfsreadreply when calling storeblock in the NFSv2 case.

An issue was discovered in Das U-Boot through 2019.07. There is an unbounded memcpy with an unvalidated length at nfsreadlinkreply, in the "if" block after calculating the new path length.

An issue was discovered in Das U-Boot through 2019.07. There is an unbounded memcpy with unvalidated length at nfsreadlinkreply in the "else" block after calculating the new path length.

An issue was discovered in Das U-Boot through 2019.07. There is an unbounded memcpy when parsing a UDP packet due to a netprocessreceivedpacket integer underflow during an ncinputpacket call.

A crafted self-referential DOS partition table will cause all Das U-Boot versions through 2019.07-rc4 to infinitely recurse, causing the stack to grow infinitely and eventually either crash or overwrite other data.