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CVE-2026-89720

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.7 · Élevée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, <=6.12.*, <83e1aa9f5f906c9b1f4949d0521f0f950a159d96, 5.15.221, <f76b79d6e42af20682495bccd22f72c7164b0018, 5.10.270, 0, <8cc3da72cf57acb4b77442ea8cec48425dff7c06, 7.2.4, 6.1.188, <=5.10.*, <=6.6.*, <a1dc246f98bb94233effa4fa3ec7bf84700bb7d1, 6.6.157, 5.3, <95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf, <=6.18.*, <5.3, 817aa094842dfc3a6b98c9582d4a647827f66201, <=7.2.*, <=*, <=5.15.*, <ab7405bd86331cc2dbc8201699d4adc33bea75e7, <11abc34698cb3172badf8aa12e623f1bac98bbd8, <37a9d25a563f5f9103282954ce573c4a61321e7c, 6.18.50, 6.12.109, 7.3

Description

In the Linux kernel, the following vulnerability has been resolved: ubifs: fix out-of-bounds read in signature length check ubifs_sb_verify_signature() bounds the on-disk ubifs_sig_node->len field before handing the signature payload to verify_pkcs7_signature(), but the check has the wrong sign: if (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node)) The signature bytes start sizeof(struct ubifs_sig_node) (UBIFS_SIG_NODE_SZ, 64 bytes) into the node, so the payload is at most snod->len - sizeof(struct ubifs_sig_node) bytes long. Adding the header size instead of subtracting it accepts a declared length up to 2 * UBIFS_SIG_NODE_SZ larger than the node actually holds -- past the end of c->sbuf, which is vmalloc(c->leb_size). verify_pkcs7_signature() -> pkcs7_parse_message() -> asn1_ber_decoder() is then handed that inflated length and reads beyond the allocation while walking the DER headers. The node length comes straight from the mounted image, so a crafted signed UBIFS image reaches this via ubifs_read_superblock() before the signature is cryptographically checked. snod->len is guaranteed to be >= UBIFS_SIG_NODE_SZ by the node scanner (c->ranges[UBIFS_SIG_NODE].min_len == UBIFS_SIG_NODE_SZ), so the corrected subtraction cannot underflow. Legitimately signed images are unaffected: a correct superblock never declares a signature longer than the node it is embedded in.

Gravité et risque d'exploitation

CVE-2026-89720 obtient un score CVSS de 7.7/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.18 %, ce qui la place devant 7.6 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <=6.12.*, <83e1aa9f5f906c9b1f4949d0521f0f950a159d96, 5.15.221, <f76b79d6e42af20682495bccd22f72c7164b0018, 5.10.270, 0, <8cc3da72cf57acb4b77442ea8cec48425dff7c06, 7.2.4, 6.1.188, <=5.10.*, <=6.6.*, <a1dc246f98bb94233effa4fa3ec7bf84700bb7d1, 6.6.157, 5.3, <95d27c1708bb6e8823c8e7c623f9abc2a91bf4bf, <=6.18.*, <5.3, 817aa094842dfc3a6b98c9582d4a647827f66201, <=7.2.*, <=*, <=5.15.*, <ab7405bd86331cc2dbc8201699d4adc33bea75e7, <11abc34698cb3172badf8aa12e623f1bac98bbd8, <37a9d25a563f5f9103282954ce573c4a61321e7c, 6.18.50, 6.12.109, 7.3) 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

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