CVE-2026-98531
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CVE Details
| Release Date: | 2026-10-18 | |
| Impact: | Important | What is this? |
Description
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.
See more information about CVE-2026-98531 from MITRE CVE dictionary and NIST NVD
NOTE: The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 metrics
| Base Score: | 3.3 |
| Vector String: | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N |
| Version: | 3.1 |
| Attack Vector: | Local |
| Attack Complexity: | Low |
| Privileges Required: | Low |
| User Interaction: | None |
| Scope: | Unchanged |
| Confidentiality Impact: | Low |
| Integrity Impact: | None |
| Availability Impact: | None |
Errata information
| Platform | Errata | Release Date |
| Oracle Linux version 10 (kernel-uek) | ELSA-2026-500572 | 2026-11-02 |
| Oracle Linux version 8 (kernel-uek) | ELSA-2026-500574 | 2026-11-02 |
| Oracle Linux version 9 (kernel-uek) | ELSA-2026-500572 | 2026-11-02 |
| Oracle Linux version 9 (kernel-uek) | ELSA-2026-500574 | 2026-11-02 |
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