In OpenBSD 7.5 before errata 008 and OpenBSD 7.4 before errata 021, avoid possible mbuf double free in NFS client and server implementation, do not use uninitialized variable in error handling of NFS server.

libc in OpenBSD 6.6 allows authentication bypass via the -schallenge username, as demonstrated by smtpd, ldapd, or radiusd. This is related to gen/authsubr.c and gen/authenticate.c in libc (and login/login.c and xenocara/app/xenodm/greeter/verify.c).

A flaw exists in OpenBSD's implementation of the stack guard page that allows attackers to bypass it resulting in arbitrary code execution using setuid binaries such as /usr/bin/at. This affects OpenBSD 6.1 and possibly earlier versions.

iked in OpenIKED, as used in OpenBSD through 6.7, allows authentication bypass because ca.c has the wrong logic for checking whether a public key matches.

x509/x509verify.c in LibreSSL before 3.4.2, and OpenBSD before 7.0 errata 006, allows authentication bypass because an error for an unverified certificate chain is sometimes discarded.

BSD compress implemented an LZW compressor and decompressor. This decompressor implementation did not correctly handle compressed streams that contain code words that were not yet added to the decompression table. LZW decompression has a special case (a KwKwK string) when code word may match the first free entry in the decompression table. The implementation used in BSD compress allow code words not only matching, but also exceeding the first free entry.

It seems this compress implementation first appeared in BSD around 1985, and was later used in various other code base, such as ncompress and gzip. Other components that contain affected code will be listed below. Following page list the version of the code as was used in 4.3BSD:

http://minnie.tuhs.org/cgi-bin/utree.pl?file=4.3BSD-Reno/src/usr.bin/compress/compress.c

Relevant code appears in the decompress() routine:

/ Special case for KwKwK string. / if ( code >= freeent ) { stackp++ = finchar; code = oldcode; }

This allows creating a loop in the decompression table, which leads to an "infinite" loop:

/ Generate output characters in reverse order / #ifdef SIGNEDCOMPARESLOW while ( ((unsigned long)code) >= ((unsigned long)256) ) { #else while ( code >= 256 ) { #endif stackp++ = tabsuffixof(code); code = tabprefixof(code); }

where tabprefixof is:

unsigned short codetab [HSIZE]; #define codetabof(i) codetab[i] #define tabprefixof(i) codetabof(i)

This overflows destack "buffer" (part of the htab[]):

countint htab [HSIZE]; # define tabsuffixof(i) ((chartype )(htab))[i] # define destack ((chartype )&tabsuffixof(1<<BITS))

Depending on the relative htab[] and codetab[] positions, destack overflow may overwrite codetab[] entries, which may break infinite loop and let program continue its execution with possibly corrupted memory.

The IPv6 Neighbor Discovery Protocol (NDP) implementation in (1) FreeBSD 6.3 through 7.1, (2) OpenBSD 4.2 and 4.3, (3) NetBSD, (4) Force10 FTOS before E7.7.1.1, (5) Juniper JUNOS, and (6) Wind River VxWorks 5.x through 6.4 does not validate the origin of Neighbor Discovery messages, which allows remote attackers to cause a denial of service (loss of connectivity) or read private network traffic via a spoofed message that modifies the Forward Information Base (FIB).

In OpenBSD 7.4 before errata 014, vmm(4) did not restore GDTR limits properly on Intel (VMX) CPUs.

regcomp in the BSD implementation of libc is vulnerable to denial of service due to stack exhaustion.

OpenBSD 6.6, in a non-default configuration where S/Key or YubiKey authentication is enabled, allows local users to become root by leveraging membership in the auth group. This occurs because root's file can be written to /etc/skey or /var/db/yubikey, and need not be owned by root.

The tcprespond function in netinet/tcpsubr.c in OpenBSD 4.1 and 4.2 allows attackers to cause a denial of service (panic) via crafted TCP packets. NOTE: some of these details are obtained from third party information.

The ip6checkrh0hdr function in netinet6/ip6input.c in OpenBSD 4.2 allows attackers to cause a denial of service (panic) via malformed IPv6 routing headers.

Integer truncation error in the amapalloc function in OpenBSD 5.8 and 5.9 allows local users to execute arbitrary code with kernel privileges via a large size value.

Integer overflow in the amapalloc1 function in OpenBSD 5.8 and 5.9 allows local users to execute arbitrary code with kernel privileges via a large size value.

In OpenBSD 6.6, local users can use the su -L option to achieve any login class (often excluding root) because there is a logic error in the main function in su/su.c.

xlock in OpenBSD 6.6 allows local users to gain the privileges of the auth group by providing a LIBGLDRIVERSPATH environment variable, because xenocara/lib/mesa/src/loader/loader.c mishandles dlopen.

The barracudavpn component of the Barracuda VPN Client prior to version 5.0.2.7 for Linux, macOS, and OpenBSD runs as a privileged process and can allow an unprivileged local attacker to load a malicious library, resulting in arbitrary code executing as root.

asciiloadsockaddr in smtpd in OpenBSD before 7.1 errata 024 and 7.2 before errata 020, and OpenSMTPD Portable before 7.0.0-portable commit f748277, can abort upon a connection from a local, scoped IPv6 address.

In OpenBSD 7.3 before errata 016, npppd(8) could crash by a l2tp message which has an AVP (Attribute-Value Pair) with wrong length.

In OpenBSD 7.4 before errata 002 and OpenBSD 7.3 before errata 019, a network buffer that had to be split at certain length that could crash the kernel after receiving specially crafted escape sequences.

OpenBSD 3.3 and 3.4 does not properly parse Accept and Deny rules without netmasks on big-endian 64-bit platforms such as SPARC64, which may allow remote attackers to bypass access restrictions.

It was found in FreeBSD 8.0, 6.3 and 4.9, and OpenBSD 4.6 that a null pointer dereference in ftpd/popen.c may lead to remote denial of service of the ftpd service.

OpenBSD kernel version <= 6.5 can be forced to create long chains of TCP SACK holes that causes very expensive calls to tcpsackoption() for every incoming SACK packet which can lead to a denial of service.

slaacd in OpenBSD 6.9 and 7.0 before 2022-03-22 has an integer signedness error and resultant heap-based buffer overflow triggerable by a crafted IPv6 router advertisement. NOTE: privilege separation and pledge can prevent exploitation.

engine.c in slaacd in OpenBSD 6.9 and 7.0 before 2022-02-21 has a buffer overflow triggerable by an IPv6 router advertisement with more than seven nameservers. NOTE: privilege separation and pledge can prevent exploitation.

In OpenBSD 7.2, a TCP packet with destination port 0 that matches a pf divert-to rule can crash the kernel.

cron/entry.c in vixie cron before 9cc8ab1, as used in OpenBSD 7.4 and 7.5, allows a heap-based buffer underflow and memory corruption. NOTE: this issue was introduced during a May 2023 refactoring.

A certain pseudo-random number generator (PRNG) algorithm that uses XOR and 3-bit random hops (aka "Algorithm X3"), as used in OpenBSD 2.8 through 4.2, allows remote attackers to guess sensitive values such as DNS transaction IDs by observing a sequence of previously generated values. NOTE: this issue can be leveraged for attacks such as DNS cache poisoning against OpenBSD's modification of BIND.

A certain pseudo-random number generator (PRNG) algorithm that uses ADD with 0 random hops (aka "Algorithm A0"), as used in OpenBSD 3.5 through 4.2 and NetBSD 1.6.2 through 4.0, allows remote attackers to guess sensitive values such as (1) DNS transaction IDs or (2) IP fragmentation IDs by observing a sequence of previously generated values. NOTE: this issue can be leveraged for attacks such as DNS cache poisoning, injection into TCP packets, and OS fingerprinting.

A certain pseudo-random number generator (PRNG) algorithm that uses XOR and 2-bit random hops (aka "Algorithm X2"), as used in OpenBSD 2.6 through 3.4, Mac OS X 10 through 10.5.1, FreeBSD 4.4 through 7.0, and DragonFlyBSD 1.0 through 1.10.1, allows remote attackers to guess sensitive values such as IP fragmentation IDs by observing a sequence of previously generated values. NOTE: this issue can be leveraged for attacks such as injection into TCP packets and OS fingerprinting.