Linux kernel vulnerability in IPsec fast path affects widely deployed kernels and VPN/networking endpoints; could disrupt enterprise infrastructure.
CVE-2026-63912
Linux kernel ESP fragment handling bug causes memory corruption in IPsec fast path
Is CVE-2026-63912 being exploited?
Not confirmed. CVE-2026-63912 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.71% probability of exploitation in the next 30 days.
How severe is CVE-2026-63912?
CVE-2026-63912 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-63912?
Yes. A fix has been recorded for CVE-2026-63912. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-63912 affect?
CVE-2026-63912 affects Linux kernel (xfrm/esp IPsec), Linux distributions with affected kernels, VPN gateways/routers running Linux. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63912?
Install vendor kernel security updates; restart IPsec services and block untrusted IPsec peers.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote kernel memory corruption via crafted ESP (IPsec) packets; may enable RCE or cause kernel panic/DoS.
Immediate action required
- affected>= c075c3ea031757f8ea2d34567565b61a868c08d5 and < 566295735530ee513326049b0540f32ec050bf2e
- affected>= a583f2f3c8788bffd7fd7baeb76bd6d80543d7ea and < 5d7ab86e2b6bc23054616bf6ac562013bf60af8c
- affected>= 5bd8baab087dff657e05387aee802e70304cc813 and < 36519e3d941fc99d3b52c134dbaf311f987a4708
- affected>= 5bd8baab087dff657e05387aee802e70304cc813 and < 322e48187e0245ab2fff6fec2220b0cae677dbec
- affected>= 5bd8baab087dff657e05387aee802e70304cc813 and < b84091ceddc9f133229dceab3ccc930bf27f9cba
- affected>= 5bd8baab087dff657e05387aee802e70304cc813 and < c093468aea8277f77272a4f199b2e15e19cabb59
- affected>= 5bd8baab087dff657e05387aee802e70304cc813 and < 65f3b3fc2347b89fe21db1e92c7681368415f095
- affected>= 5bd8baab087dff657e05387aee802e70304cc813 and < dfa0d7b0ff1eb6b2c416b8fdb9b4f2cefba57a40
- affected2c66b0c95bb0aa7652ba1eba293d0d5993b35a38
- affectedef6f83df1209a7d9bd1c605a62457d4c00f9179e
- affected3defefd22ad5fbbe639b6157fb7e6311b2bf333d
- affectedb657030870bb5351c5b1e84d4e9f186da6ca0496
- affected>= 5.10.113 and < 5.10.259
- affected>= 5.15.36 and < 5.15.210
- affected>= 4.14.288 and < 4.15
- affected>= 4.19.252 and < 4.20
- affected>= 5.4.205 and < 5.5
- affected>= 5.17.5 and < 5.18
- affected5.18
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.