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CVE-2026-98531

ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST In seg6_genl_policy, SEG6_ATTR_DST is defined with .type = NLA_BINARY and .len = sizeof(struct in6_addr). For NLA_BINARY, .len only enforces the maximum payload length and permits shorter payloads (e.g., 0 bytes). When seg6_genl_set_tunsrc() copies sizeof(struct in6_addr) bytes via kmemdup(val, sizeof(*val), GFP_KERNEL), a short SEG6_ATTR_DST attribute triggers a 16-byte out-of-bounds read past skb->tail into uninitialized skb->head memory, which is stored in sdata->tun_src and leaked back to userspace via SEG6_CMD_GET_TUNSRC. Switch SEG6_ATTR_DST in seg6_genl_policy to NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) so that generic netlink validation rejects any attribute whose length is not exactly sizeof(struct in6_addr) with -ERANGE. Tested in QEMU against Linux 7.3.0-rc3 by sending a SEG6_CMD_SET_TUNSRC Generic Netlink message with a 0-byte SEG6_ATTR_DST attribute followed by SEG6_CMD_GET_TUNSRC. On the unfixed kernel, SEG6_CMD_SET_TUNSRC succeeds (err = 0) and SEG6_CMD_GET_TUNSRC leaks 16 bytes of uninitialized kernel heap memory (tun_src = 836a61ecc4d25a1042a8d60411cfb378); with this patch applied, SEG6_CMD_SET_TUNSRC is rejected by netlink policy validation with -ERANGE (-34) and tun_src remains zeroed.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in 050a0aa3c80907b8c60a396b7e04d48d8b1a9e70; From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in 209eefebee54c4a5f01d68b61e8ac9881eca2de9; From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in e3ac68c1cdc2535d127b2bfd50c263d16c8e4199; From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in 66bf65fa109326e4c4ddeb0b94093379f72838fd; From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in 195813bb7324c338eaba0aaa02b18681ee65b670; From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in 6fcfc362344edea745a69f3a705de50b731f3418; From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in 94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e; From 915d7e5e5930b4f01d0971d93b9b25ed17d221aa · fixed in 2d959c75c27f90e9ec489d18ce5ee6b852ad4741

  • Linux Linux

    4.10

  • KernelLinux

    From 4.10.0 · fixed in 5.10.271; From 5.11.0 · fixed in 5.15.222; From 5.16.0 · fixed in 6.1.189; From 6.2.0 · fixed in 6.6.158; From 6.7.0 · fixed in 6.12.112; From 6.13.0 · fixed in 6.18.55; From 6.19.0 · fixed in 7.2.9

References 8

git.kernel.org