CVE-2026-23455 (GCVE-0-2026-23455)
Vulnerability from cvelistv5
Published
2026-04-03 15:15
Modified
2026-08-05 12:21
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.
Impacted products
Vendor Product Version
Linux Linux Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
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Show details on NVD website


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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_h323: check for zero length in DecodeQ931()\n\nIn DecodeQ931(), the UserUserIE code path reads a 16-bit length from\nthe packet, then decrements it by 1 to skip the protocol discriminator\nbyte before passing it to DecodeH323_UserInformation(). If the encoded\nlength is 0, the decrement wraps to -1, which is then passed as a\nlarge value to the decoder, leading to an out-of-bounds read.\n\nAdd a check to ensure len is positive after the decrement."
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              "value": "AV:N - The vulnerable H.323/Q.931 conntrack helper parses TCP network traffic, typically on H.323 call signaling flows through a firewall/NAT gateway. A remote peer can supply the malformed TPKT/Q.931 packet once the helper is active for that flow.\nAC:L - The trigger is a deterministic zero-length UserUserIE in an otherwise reachable Q.931 message; there is no race or condition outside the attacker\u0027s control. TCP establishment and helper deployment are normal operating conditions for the affected subsystem.\nPR:N - The attacker only needs to send network traffic to or through a system using the H.323 conntrack helper. No authentication or local privileges are required on the target system.\nUI:N - Exploitation occurs during automatic packet processing in the kernel netfilter path. No victim user action is required.\nS:U - The vulnerable component and impacted resources are within the same kernel/network filtering security authority. This is not a VM escape, IOMMU bypass, or cross-sandbox boundary violation.\nC:H - The integer underflow turns a zero encoded length into a huge decoder length, causing an out-of-bounds read beyond the packet buffer. Under the kernel guidance, an unbounded out-of-bounds read is High confidentiality impact.\nI:N - The bug is a read-side parser bounds failure and does not provide an out-of-bounds write, arbitrary write primitive, or direct control-flow corruption. Any resulting malformed conntrack processing is not enough to justify kernel data integrity compromise.\nA:H - The out-of-bounds read can fault or otherwise destabilize kernel packet processing, producing an oops/panic or repeated denial of service. A remote attacker can resend malformed packets to retrigger it."
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          "url": "https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23455",
    "datePublished": "2026-04-03T15:15:36.869Z",
    "dateReserved": "2026-01-13T15:37:46.020Z",
    "dateUpdated": "2026-08-05T12:21:54.080Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
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