CVE-2026-90110
9.4 CRITICALPublished 2026-09-17 · Updated 2026-09-18
AI risk analysis
- Summary
- This flaw allows an off-path adversary to predict the RB-tree node comparisons in the inetpeer rate-limiting system, potentially evicting targeted nodes and resetting their rate-limiting tokens, thereby bypassing IP-keyed ICMP rate limits and inferring open UDP ports.
- Exploitability
- Exploitation requires knowledge of the secret key and the ability to predict the tree traversal, making it moderately difficult. Precondition is access to the network and understanding of the system's internal workings.
- Blast radius
- If exploited, this could lead to unauthorized access and port inference on affected systems, impacting network security and potentially allowing further attacks.
- Detection
- No reliable host or network indicator is derivable from the published description.
- Prioritized remediation
- Upgrade to the Linux kernel version 6.2.0 or later, which includes the fix for this vulnerability.
Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.
NVD description
In the Linux kernel, the following vulnerability has been resolved: inetpeer: randomize RB-tree node comparison using SipHash The inetpeer rate limiting system stores peer entries in a Red-Black tree keyed deterministically on the remote IP address. Because tree lookups walk the RB-tree using standard lexicographical comparisons (inetpeer_addr_cmp), an off-path adversary can predict the exact topology of the tree and the sequence of nodes traversed during lookups (the gc_stack candidate list). By combining deterministic tree traversal with aggressive garbage collection (triggered when tree size exceeds inet_peer_threshold), an attacker can selectively force the eviction of targeted inet_peer nodes. When an evicted node is subsequently re-created upon receiving a new packet, its rate-limiting token bucket (rate_tokens, rate_last) is reset to full capacity. This creates a side-channel primitive allowing off-path attackers to bypass IP-keyed ICMP rate limits and infer open UDP ports (similar to SAD DNS style attacks). Mitigate this by randomizing the RB-tree node comparison logic using SipHash with a secret key (inetpeer_hash_key) initialized via net_get_random_once(). Nodes are ordered in the tree by SipHash(addr, key) rather than raw IP addresses. Because the secret key is unknown to external entities, the tree layout and lookup traversal paths are unpredictable to off-path adversaries, breaking the deterministic eviction gadget. Cache the computed 64-bit SipHash (hash) in struct inet_peer and compute the target hash (dhash) once at the beginning of inet_getpeer() to avoid recomputing SipHash at every step of the RB-tree walk.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
All references
- https://git.kernel.org/stable/c/199fcf285e498111e029137d088949bc6c26d578
- https://git.kernel.org/stable/c/2ee66e9487172fcd189bc52a767c30dad7141c09
- https://git.kernel.org/stable/c/5f127e3cc9647a8a70db12c65dbd0de473545380
- https://git.kernel.org/stable/c/7109bb63667a53e4542ad845476f97d0c8b28a61
- https://git.kernel.org/stable/c/857681f6835d5b0a7bc4a34a026baeaaf5215623
- https://git.kernel.org/stable/c/b20e98f0bb668a59abaf7bcf85d75c073e90d352
Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.
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