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VulnerabilityPublished Updated

CVE-2026-64102: Linux kernel · Integer Overflow

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2, 1012896f4225e8f801ff3c1648023845b66dfb11, 14553be882d9ce91749c9d64041de66e34ad8e70 +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2
Fixed in
  • c7c0c0f4379dedec12d24dbb9dded5d2db7fd9f2
LinuxLinuxAffected
  • ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 1012896f4225e8f801ff3c1648023845b66dfb11
Fixed in
  • 1012896f4225e8f801ff3c1648023845b66dfb11
LinuxLinuxAffected
  • ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 14553be882d9ce91749c9d64041de66e34ad8e70
Fixed in
  • 14553be882d9ce91749c9d64041de66e34ad8e70
LinuxLinuxAffected
  • ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 775b4dc9618a99a1fa48b57554041a5dc17e1336
Fixed in
  • 775b4dc9618a99a1fa48b57554041a5dc17e1336
LinuxLinuxAffected
  • ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 683f7cfbf514193d63c0efa079f3352bde84c2e0
Fixed in
  • 683f7cfbf514193d63c0efa079f3352bde84c2e0
LinuxLinuxAffected
  • ≥ 8b6a361b8c482f22ac99c3273285ff16b23fba91, < 33a8b5e971e294ec2a7b74211c545e09efd8e9ac
Fixed in
  • 33a8b5e971e294ec2a7b74211c545e09efd8e9ac

Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/siw: Reject MPA FPDU length underflow before signed receive math A malicious connected siw peer can send an iWARP FPDU whose MPA length field (c_hdr->mpa_len, 16 bit big-endian, peer-controlled) is smaller than the fixed DDP/RDMAP header for the announced opcode. Soft-iWARP parses the full header in siw_get_hdr() based on iwarp_pktinfo[opcode] .hdr_len, but never compares mpa_len against that header length. siw_tcp_rx_data() then derives srx->fpdu_part_rem = be16_to_cpu(mpa_len) - fpdu_part_rcvd + MPA_HDR_SIZE; where fpdu_part_rcvd equals iwarp_pktinfo[opcode].hdr_len at this point. For a tagged WRITE (hdr_len 16, MPA_HDR_SIZE 2) the smallest on-wire mpa_len of 0 yields fpdu_part_rem = -14, and any mpa_len below hdr_len - MPA_HDR_SIZE underflows to a negative int. The signed value then flows into siw_proc_write()/siw_proc_rresp() as bytes = min(srx->fpdu_part_rem, srx->skb_new); is handed to siw_check_mem() as an int len (whose interval check addr + len > mem->va + mem->len is satisfied for a valid base when len is negative), and reaches siw_rx_data() -> siw_rx_kva() / siw_rx_umem() -> skb_copy_bits() as a signed copy length. The header copy branch in skb_copy_bits() promotes that to size_t, producing a multi-gigabyte read. KASAN under a KUnit harness that drives the real kernel TCP receive path -- a loopback AF_INET socketpair, the malformed FPDU written via kernel_sendmsg, sk_data_ready firing in softirq, tcp_read_sock dispatching to siw_tcp_rx_data -- reports: BUG: KASAN: use-after-free in skb_copy_bits+0x284/0x480 Read of size 4294967295 at addr ffff888... Call Trace: skb_copy_bits siw_rx_kva siw_rx_data siw_check_mem siw_proc_write siw_tcp_rx_data __tcp_read_sock siw_qp_llp_data_ready tcp_data_ready tcp_data_queue Add the missing invariant at the earliest point where the peer header is fully assembled. iwarp_pktinfo[*].hdr_len - MPA_HDR_SIZE is exactly the value the siw transmitter uses as the minimum mpa_len for each opcode (drivers/infiniband/sw/siw/siw_qp.c:33), so this matches the protocol contract. Out-of-range FPDUs terminate the connection with TERM_ERROR_LAYER_LLP / LLP_ETYPE_MPA / LLP_ECODE_FPDU_START -- which is RFC 5044 Section 8 error code 3 ("Marker and ULPDU Length fields do not agree on the start of an FPDU"), the correct framing-error class for this inconsistency.

References

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