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CVE-2026-89541

Vulnérabilité critique dans Linux (Linux)

CVSS 9.8 · Critique
EPSS 0.5%
Linux•Linux•Versions : <=6.1.*, <87831b92112c81db251d46756d65daa4f91af6a2, <=6.12.*, 5.15.221, 5.10.270, 0, 7.2.4, 6.1.188, 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf, <=5.10.*, <=6.6.*, 6.6.157, <85fa6b12e8f439739ac36ef2aad925f37c8b976a, <401f6a5b338d05bb1069ad814d9f77e3c367854f, <2.6.15, <ebcbd2523a8524c3d24e111cdbed8e271d910269, <=6.18.*, 7.3, <=7.2.*, 2.6.15, <=*, <=5.15.*, <3691c4b3488d8ca046b9941e5be30c626dbbbb50, <89a15a50f84d32d4b99db86f957427fcbe20a99a, <d395c30d570ca6168f0297b191709927d1258273, 6.18.50, 6.12.109, <81fd7654a8429718adfcb2a7e03496077f547ed0

Description

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").

Gravité et risque d'exploitation

CVE-2026-89541 obtient un score CVSS de 9.8/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.51 %, ce qui la place devant 42.5 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <87831b92112c81db251d46756d65daa4f91af6a2, <=6.12.*, 5.15.221, 5.10.270, 0, 7.2.4, 6.1.188, 2d2da60c63b67174add32f06e8d54c3a0c5cd9cf, <=5.10.*, <=6.6.*, 6.6.157, <85fa6b12e8f439739ac36ef2aad925f37c8b976a, <401f6a5b338d05bb1069ad814d9f77e3c367854f, <2.6.15, <ebcbd2523a8524c3d24e111cdbed8e271d910269, <=6.18.*, 7.3, <=7.2.*, 2.6.15, <=*, <=5.15.*, <3691c4b3488d8ca046b9941e5be30c626dbbbb50, <89a15a50f84d32d4b99db86f957427fcbe20a99a, <d395c30d570ca6168f0297b191709927d1258273, 6.18.50, 6.12.109, <81fd7654a8429718adfcb2a7e03496077f547ed0) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

Rechercher une autre CVE