CVE-2026-68315

In the Linux kernel, the following vulnerability has been resolved:

sctp: validate stream count in sctp_process_strreset_inreq()

When processing a RESET_IN_REQUEST from a peer, sctp_process_strreset_inreq() derives the stream count from the parameter length but does not check whether the resulting RESET_OUT_REQUEST would exceed SCTP_MAX_CHUNK_LEN.

The OUT request header (sctp_strreset_outreq, 16 bytes) is 8 bytes larger than the IN request header (sctp_strreset_inreq, 8 bytes). Generally, the IP payload is bounded to 65535 bytes, so the stream list cannot be large enough to trigger the overflow. However, on interfaces with MTU > 65535 (e.g., loopback with IPv6 jumbograms), a stream list that fits within the incoming IN parameter can cause a __u16 overflow in sctp_make_strreset_req() when computing the OUT request size, leading to an undersized skb allocation and a kernel BUG:

net/core/skbuff.c:207 skb_panic net/core/skbuff.c:2625 skb_put net/sctp/sm_make_chunk.c:1535 sctp_addto_chunk net/sctp/sm_make_chunk.c:3695 sctp_make_strreset_req net/sctp/stream.c:655 sctp_process_strreset_inreq

The local setsockopt path validates the generated reset request size. However, for an incoming-only reset, it accounts for the smaller IN request even though the peer must generate an OUT request with the same stream list. Such a request cannot be completed successfully by the peer.

Reject peer IN requests whose corresponding OUT request would exceed SCTP_MAX_CHUNK_LEN. Also tighten the local check so it does not send an IN request that would require an oversized OUT request from the peer.

Weakness

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• If possible, choose a language or compiler that performs automatic bounds checking.
• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
• Use libraries or frameworks that make it easier to handle numbers without unexpected consequences.
• Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
• Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
• Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values.
• Understand the programming language’s underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, “not-a-number” calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7]
• Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/92.html

References

• https://git.kernel.org/stable/c/00ae679cb21a035491fdad8d58dc6d79cc68b675
• https://git.kernel.org/stable/c/18ae07691d43183d270de8be9dc8e027906015d9
• https://git.kernel.org/stable/c/1a10fe1aa9c01f41b389a31906a77d538637c9d9
• https://git.kernel.org/stable/c/60c47dea5d320d2fc706e9aad1db38a04df0a056
• https://git.kernel.org/stable/c/61327d8e7cfb0259d527be17202630f556213249
• https://git.kernel.org/stable/c/6f0e39d180cd7cced647381b6fa14fd83d261047
• https://git.kernel.org/stable/c/7cf7439948e3bf639119119922c88ec190874ca3
• https://git.kernel.org/stable/c/b255d8cd6cc68045ae9eecbac3b3c14e1f176c9b