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.

An update of the linux package has been released.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-89720)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
375048	Photon OS 5.0: Linux PHSA-2026-5.0-92-0999	Nessus	PhotonOS Local Security Checks	Local	high
375011	Photon OS 5.0: Linux PHSA-2026-5.0-91-0999	Nessus	PhotonOS Local Security Checks	Local	high
366919	Debian dla-4841 : ata-modules-6.1.0-53-armmp-di - security update	Nessus	Debian Local Security Checks	Local	high
362907	Debian dla-4817 : ata-modules-6.12.107+deb12-armmp-di - security update	Nessus	Debian Local Security Checks	Local	high
351155	Debian dsa-6528 : ata-modules-6.12.111+deb13-armmp-di - security update	Nessus	Debian Local Security Checks	Local	high
345089	Linux Distros Unpatched Vulnerability : CVE-2026-89720	Nessus	Misc.	Local	high

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CVE-2026-89720

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Tenable Plugins

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