CVE-2026-89541SUNRPC: harden gss_unwrap_resp_priv length checks
Updated under an hour ago ()
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In the Linux kernel, the following vulnerability has been resolved: SUNRPC: harden gss_unwrap_resp_priv length checks gss_unwrap_resp_priv() validates the RPCSEC_GSS opaque length with offset = (u8 *)(p) - (u8 *)head->iov_base; if (offset + opaque_len > rcv_buf->len) goto unwrap_failed; maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset, offset + opaque_len, rcv_buf); Both operands are u32 and the sum is computed in u32. A reply with opaque_len near 0xffffffff makes offset + opaque_len wrap to a small value that is below rcv_buf->len, so the bound check passes and gss_unwrap() is called with end < begin. The check also lacks a lower bound, so any opaque_len in [0, GSS_KRB5_TOK_HDR_LEN) is accepted and forwarded to gss_krb5_unwrap_v2(), whose pre-decrypt header reads at ptr+4 and ptr+6 then run past the token. A krb5p NFS server returning a crafted RPCSEC_GSS reply can drive the client into out-of-bounds reads in gss_krb5_unwrap_v2() and the rotate_left() loop that follows. Fix by replacing the single combined check with three guards that are safe in u32 arithmetic and that enforce the RFC 4121 minimum outer token length: if (offset > rcv_buf->len) goto unwrap_failed; if (opaque_len > rcv_buf->len - offset) goto unwrap_failed; if (opaque_len < GSS_KRB5_TOK_HDR_LEN) goto unwrap_failed; The first guard makes the subtraction in the second guard unconditionally safe; offset is derived from a successful xdr_inline_decode() in the head kvec, so in practice it already satisfies the bound. The floor mirrors the server-side check added in commit 5b757c2e57a5 ("SUNRPC: svcauth_gss: enforce krb5 token minimum length").
- CVSS
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before 3691c4b3488d8ca046b9941e5be30c626dbbbb50; from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before 85fa6b12e8f439739ac36ef2aad925f37c8b976a; from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before 401f6a5b338d05bb1069ad814d9f77e3c367854f; from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before 81fd7654a8429718adfcb2a7e03496077f547ed0; from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before 89a15a50f84d32d4b99db86f957427fcbe20a99a; from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before ebcbd2523a8524c3d24e111cdbed8e271d910269; from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before d395c30d570ca6168f0297b191709927d1258273; from 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf before 87831b92112c81db251d46756d65daa4f91af6a2 | CNA record |
References
- https://git.kernel.org/stable/c/3691c4b3488d8ca046b9941e5be30c626dbbbb50
- https://git.kernel.org/stable/c/85fa6b12e8f439739ac36ef2aad925f37c8b976a
- https://git.kernel.org/stable/c/401f6a5b338d05bb1069ad814d9f77e3c367854f
- https://git.kernel.org/stable/c/81fd7654a8429718adfcb2a7e03496077f547ed0
- https://git.kernel.org/stable/c/89a15a50f84d32d4b99db86f957427fcbe20a99a
- https://git.kernel.org/stable/c/ebcbd2523a8524c3d24e111cdbed8e271d910269
- https://git.kernel.org/stable/c/d395c30d570ca6168f0297b191709927d1258273
- https://git.kernel.org/stable/c/87831b92112c81db251d46756d65daa4f91af6a2
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.