Unspecified impact via incorrect tunnel header length
Published Sep 11, 2026 · Updated Sep 11, 2026
Incorrect header-length accounting in Linux ip6_gre allows attackers to cause an unspecified impact through an NBMA IPv6 GRE tunnel. ip6gre_tnl_link_config_route() adds the lower device's hardware-header length to hard_header_len even though that value is only later-required headroom; tap and ERSPAN devices also retain a fixed Ethernet header length. Reachability requires an NBMA ip6gre, ip6gretap, or ip6erspan configuration, and the upstream record does not state the resulting security consequence.
Summary
What happened
Incorrect header-length accounting in Linux ip6_gre allows attackers to cause an unspecified impact through an NBMA IPv6 GRE tunnel. ip6gre_tnl_link_config_route() adds the lower device's hardware-header length to hard_header_len even though that value is only later-required headroom; tap and ERSPAN devices also retain a fixed Ethernet header length. Reachability requires an NBMA ip6gre, ip6gretap, or ip6erspan configuration, and the upstream record does not state the resulting security consequence.
The record
- CVE
- CVE-2026-89562
- Published
- Sep 11, 2026
- Updated
- Sep 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 11, 2026CVE publishedPublication date reported by the CVE source.
- Sep 11, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=187a6daf5db45adc807c85bbe285319107bed198
- Affected versionversion=4.19.162 <4.20
- Affected versionversion=5.10
- Affected versionversion=5.4.82 <5.5
- Affected versionversion=5.9.13 <5.10
- Affected versionversion=832ba596494b2c9eac7760259eff2d8b7dcad0ee <505b6d296c486ef7d1274f279d4c43a172f63224
- Affected versionversion=832ba596494b2c9eac7760259eff2d8b7dcad0ee <565038b0092f65afe384961c0f548d605bf438b9
- Affected versionversion=832ba596494b2c9eac7760259eff2d8b7dcad0ee <8bfe746afee38dd6e4348ddcd22d554789dbb9ff
- Affected versionversion=832ba596494b2c9eac7760259eff2d8b7dcad0ee <b8282668d8fa7c61b80e8e4890729031c291a16c
- Affected versionversion=cf3d9717a5271573fa193c4dfa0df856295d5b15
- Affected versionversion=d9897bb66ce989325b4bf4cdbb6a799e4ac878b6
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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Your stack
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