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CVE-2026-43233

netfilter: nf_conntrack_h323: fix OOB read in decode_choice()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_choice() In decode_choice(), the boundary check before get_len() uses the variable `len`, which is still 0 from its initialization at the top of the function: unsigned int type, ext, len = 0; ... if (ext || (son->attr & OPEN)) { BYTE_ALIGN(bs); if (nf_h323_error_boundary(bs, len, 0)) /* len is 0 here */ return H323_ERROR_BOUND; len = get_len(bs); /* OOB read */ When the bitstream is exactly consumed (bs->cur == bs->end), the check nf_h323_error_boundary(bs, 0, 0) evaluates to (bs->cur + 0 > bs->end), which is false. The subsequent get_len() call then dereferences *bs->cur++, reading 1 byte past the end of the buffer. If that byte has bit 7 set, get_len() reads a second byte as well. This can be triggered remotely by sending a crafted Q.931 SETUP message with a User-User Information Element containing exactly 2 bytes of PER-encoded data ({0x08, 0x00}) to port 1720 through a firewall with the nf_conntrack_h323 helper active. The decoder fully consumes the PER buffer before reaching this code path, resulting in a 1-2 byte heap-buffer-overflow read confirmed by AddressSanitizer. Fix this by checking for 2 bytes (the maximum that get_len() may read) instead of the uninitialized `len`. This matches the pattern used at every other get_len() call site in the same file, where the caller checks for 2 bytes of available data before calling get_len().

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • Linux Linux

    From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041; From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in 2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a; From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in 81f2fc5b0d0cf4696146f00f837596d10b92dead; From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in 7ef82863d42261817a6394c6c881bd6757a70f16; From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in 53d32735d77ab56cc3fc7bd53a7d099418f19be1; From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in f0a83d0a4b7c127d32ac06d607a9214937716129; From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in 35f1943d242e1b9f0b6e91c0c93bfb293a9f8224; From ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa · fixed in baed0d9ba91d4f390da12d5039128ee897253d60

  • Linux Linux

    4.15

  • KernelLinux

    From 4.15.0 · fixed in 5.10.252; From 5.11.0 · fixed in 5.15.202; From 5.16.0 · fixed in 6.1.165; From 6.2.0 · fixed in 6.6.128; From 6.7.0 · fixed in 6.12.75; From 6.13.0 · fixed in 6.18.16; From 6.19.0 · fixed in 6.19.6

References 8

git.kernel.org