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9.1
CVE-2026-89537: Linux kernel NFS server may read beyond short checksum
CVE-2026-89537 · published 1 month ago
Summary
The Linux kernel’s NFS code could accept unusually short security tokens from a malicious NFS server, causing it to read past the end of allocated memory. This can lead to crashes or potential exploitation. Updating to a kernel version that includes the fix prevents the kernel from processing these undersized tokens.
What to do
- Update debian linux to version 7.2.6-1.
- Update linux kernel to version 7.2.4.
- Update linux linux to version 7a946b2e7207f968902f2147ab9b30726f82f7ab or later.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Debian:12 | debian | linux | All versions |
| Debian:14 | debian | linux |
< 7.2.6-1 Fix: upgrade to 7.2.6-1
|
| – | linux | linux |
< 7a946b2e7207f968902f2147ab9b30726f82f7ab 2.6.35 |
| Linux | linux | kernel |
>= 2.6.35, < 7.2.4 Fix: upgrade to 7.2.4
|
| Ubuntu:Pro:14.04:LTS | canonical | linux | All versions |
| Ubuntu:Pro:14.04:LTS | canonical | linux-aws | All versions |
| Ubuntu:Pro:14.04:LTS | canonical | linux-azure | All versions |
| Ubuntu:Pro:14.04:LTS | canonical | linux-lts-xenial | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-aws-hwe | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-gcp | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-hwe | All versions |
| Ubuntu:16.04:LTS | canonical | linux-hwe-edge | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-kvm | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-oracle | All versions |
| Ubuntu:Pro:FIPS:16.04:LTS | canonical | linux-fips | All versions |
| Ubuntu:18.04:LTS | canonical | linux-aws-5.0 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-aws-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-aws-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-azure-4.15 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-azure-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-azure-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-azure-edge | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-gcp-4.15 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gcp-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-gcp-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gke-4.15 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gke-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gkeop-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-hwe-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-ibm-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-oem | All versions |
| Ubuntu:18.04:LTS | canonical | linux-oracle-5.0 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-oracle-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-oracle-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-raspi-5.4 | All versions |
| Ubuntu:Pro:FIPS-updates:18.04:LTS | canonical | linux-aws-fips | All versions |
| Ubuntu:Pro:FIPS-updates:18.04:LTS | canonical | linux-azure-fips | All versions |
| Ubuntu:Pro:FIPS-updates:18.04:LTS | canonical | linux-gcp-fips | All versions |
| Ubuntu:20.04:LTS | canonical | linux-aws-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-aws-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-aws-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-aws-5.8 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-azure-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-5.8 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-fde | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-azure-fde-5.15 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-bluefield | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gcp-5.11 | All versions |
Showing 50 of 176. Show the rest
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Ubuntu:20.04:LTS | canonical | linux-gcp-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-gcp-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gcp-5.8 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gke | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gke-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gkeop | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gkeop-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-hwe-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-hwe-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-hwe-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-hwe-5.8 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-ibm | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-ibm-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-intel-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-intel-iotg-5.15 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-iot | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-lowlatency-hwe-5.15 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-nvidia-tegra-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.10 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.13 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.14 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.6 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oracle-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oracle-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-oracle-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oracle-5.8 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-raspi | All versions |
| Ubuntu:20.04:LTS | canonical | linux-raspi2 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-riscv | All versions |
| Ubuntu:20.04:LTS | canonical | linux-riscv-5.11 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-riscv-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-riscv-5.8 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-xilinx-zynqmp | All versions |
| Ubuntu:22.04:LTS | canonical | linux-allwinner-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-fde-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-fde-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-fde-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-ibm-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-intel-iot-realtime | All versions |
| Ubuntu:22.04:LTS | canonical | linux-intel-iotg | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-tegra | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-tegra-igx | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-5.17 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-6.0 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-6.1 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oracle-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oracle-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-realtime | All versions |
| Ubuntu:22.04:LTS | canonical | linux-riscv-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-riscv-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-riscv-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-starfive-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-starfive-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-starfive-6.5 | All versions |
| Ubuntu:Pro:Realtime:22.04:LTS | canonical | linux-realtime-6.8 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-aws-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-aws-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-aws-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-fde-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-fde-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-fde-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-nvidia | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-nvidia-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-lowlatency-hwe-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-lowlatency | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.8 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oracle-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oracle-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oracle-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-raspi-realtime | All versions |
| Ubuntu:24.04:LTS | canonical | linux-riscv-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-riscv-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-riscv-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-xilinx | All versions |
| Ubuntu:Pro:Realtime:24.04:LTS | canonical | linux-realtime-6.14 | All versions |
| Ubuntu:Pro:Realtime:24.04:LTS | canonical | linux-realtime-6.17 | All versions |
| Ubuntu:26.04:LTS | canonical | linux-nvidia-bos | All versions |
| Ubuntu:26.04:LTS | canonical | linux-oem-7.0 | All versions |
| Alpaquita:23 | bellsoft | linux-lts | >= 6.1.182-r0 |
| Alpaquita:25 | bellsoft | linux-lts | >= 6.12.103-r0 |
| Alpaquita:stream | bellsoft | linux-lts | >= 6.18.46-r0 |
| Ubuntu:24.04:LTS | canonical | linux-vmware | All versions |
Original advisory text
SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2
In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2 gss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags byte at ptr[2], and padding at ptr[3..7], then passes ptr + GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg(). None of these accesses check read_token->len first. The minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus ctx->krb5e->cksum_len (12-24, depending on the enctype). All callers accept shorter tokens from the wire: - gss_unwrap_resp_integ() enforces only an upper bound (offset + len <= rcv_buf->len) before allocating mic.data = kmalloc(len) and passing it to gss_verify_mic(). A malicious NFS server can therefore supply a short checksum opaque, producing a small slab allocation that the Kerberos MIC verifier reads past. - gss_validate() enforces only len <= RPC_MAX_AUTH_SIZE (400) before passing the wire-supplied length to gss_validate_seqno_mic(), which constructs a mic xdr_netobj and calls gss_verify_mic(). - svcauth_gss_verify_header() enforces only checksum.len >= XDR_UNIT (4 bytes) before dispatching to gss_verify_mic(). - svcauth_gss_unwrap_integ() checks only that the checksum fits in gsd->gsd_scratch. Add a length guard at the top of gss_krb5_verify_mic_v2(), before any ptr[] access or scatterlist construction. Well-formed MIC tokens from gss_krb5_get_mic_v2() already have exactly GSS_KRB5_TOK_HDR_LEN + cksum_len bytes, so valid traffic is unaffected.
References
- https://security-tracker.debian.org/tracker/CVE-2026-89537 Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git Product
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89537... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-89537 Vendor Advisory
- https://docs.bell-sw.com/security/cves/CVE-2026-89537 Vendor Advisory
- https://ubuntu.com/security/CVE-2026-89537 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-89537 Third Party Advisory
- https://git.kernel.org/linus/b94f6719dcd9f7a609bc5f459f85795900e77d25 Third Party Advisory
- https://git.kernel.org/stable/c/b94f6719dcd9f7a609bc5f459f85795900e77d25 Third Party Advisory
- https://git.kernel.org/stable/c/7a946b2e7207f968902f2147ab9b30726f82f7ab Third Party Advisory
Severity
9.1
Critical
Timeline
Published11 Sep 2026
Updated12 Oct 2026
First seen11 Sep 2026
Sources
CVE-2026-89537 · NVD
CVE-2026-89537 · MITRE
DEBIAN-CVE-2026-89537 · OSV
CVE-2026-89537 · OSV
UBUNTU-CVE-2026-89537 · OSV
BELL-CVE-2026-89537 · OSV
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