CVE-2026-76787
MediumCVSS 5.9Exploitation Probability (EPSS)
Low risk30th percentile - higher than 30% of all known CVEs
Summary
The UpdateHub firmware-over-the-air client in Zephyr parses the CoAP probe response with the JSON library, which treats every descriptor field as optional. When the response omits the "sha256sum" field, the corresponding pointer stays NULL and the code calls strlen() on it before any validation, causing a read at address zero. Because the metadata is supplied entirely by the network peer (plain CoAP over UDP by default, without DTLS), an attacker can trigger the fault remotely.
Risk Assessment
On targets where the low address range is unmapped or protected (e.g. MMU-based architectures, TrustZone, nRF54L), the load faults and Zephyr's fatal handler halts the system, giving a remotely re-triggerable denial of service on every poll. The impact is availability only — there is no memory write and no information-disclosure channel.
Recommendation
Update Zephyr to a version containing the fix that adds an explicit sha256sum == NULL check before strlen() in both metadata branches. Consider enabling CONFIG_UPDATEHUB_DTLS=y to restrict metadata delivery to an authenticated update server.
Related vulnerabilities
- CVE-2026-122051Critical
A flaw was found in Edimax BR-6208AC version 1.32 in an unknown functionality of the /goform/mp file. Input manipulation can lead to command injection. The attack can be launched remotely and the exploit has been published.
- CVE-2026-54384Critical
VitaFit cloud API before 2026-10-30 contained an authentication bypass vulnerability that allows remote attackers to obtain a full session for a victim's account by submitting a linked Google or Facebook account identifier to the POST /front/login/sns/ endpoint without providing proof of ownership from the identity provider. Attackers can forge a login using an identifier exposed through account enumeration to read and modify the victim's profile and delete the account's authentication record.
- CVE-2026-52848Critical
GLPI is a free asset and IT management software package. From 11.0.0 until 11.0.8, during the login phase, an unauthenticated user could use a crafted URL to skip one-time-password verification, defeating two-factor authentication. This issue is fixed in version 11.0.8.
- CVE-2026-115770Critical
Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to services. From 2.2.0 until 2.12.0, SendEmailVerification binds an email-verification token only to the user's identifier, while UpdateUser can change the account email without invalidating the outstanding token and VerifyEmail marks the current address as verified. An ordinary user can request a token for an address they control, change the account to an arbitrary unused address, and redeem the old token so Pocket ID publishes the new address with email_verified set to true.
- CVE-2026-97693Critical
Yuxi from 0.6.0.beta1 until 0.7.1 has insufficient isolation between execution-capable Docker sandboxes and trusted application services. A low-privileged authenticated user can reach other tenants' sandbox APIs, access their files and secrets, execute commands in active sandboxes, and enumerate, create, or delete sandboxes through the unauthenticated provisioner without knowing administrator, database, or MinIO credentials.
- CVE-2026-57566Critical
Readest prior to 0.11.10 contains an unauthenticated /api/opds/proxy route that fetches an attacker-controlled URL server-side without restricting the scheme, blocking private, loopback, link-local, or metadata hosts, or revalidating destinations during redirects. The route also accepts caller-controlled outbound headers and Authorization values and reflects the upstream status and response body.
- CVE-2026-54378Critical
VitaFit cloud API before 2026-10-30 contained a broken access control vulnerability that allows any authenticated user to obtain temporary AWS credentials by calling the POST /front/user/s3/token/ endpoint. Attackers can use these improperly scoped credentials to list the shared storage bucket and read or overwrite other users' stored files.
- CVE-2026-102895Critical
GPUStack prior to 2.2.0 treated a loopback request source as the built-in administrator when force_auth_localhost was false, which was the default. A remote request could appear to originate from 127.0.0.1, allowing unauthenticated administrative access, including user and model changes, persistent administrator API-key creation, disclosure of worker and cloud-provider secrets, and code execution.
- CVE-2026-102894Critical
GPUStack from 0.7.1 until 2.2.2 contains an /auth/saml/callback endpoint that decodes SAML XML and uses its NameID and attributes to resolve or provision a user without verifying the signature, issuer, audience, destination, or time conditions. Any network client could submit an identity for an existing user, including an administrator, or provision a new account, even when SAML was not configured.
- CVE-2026-82418Critical
IBM Watson Speech Services Cartridge versions 4.0.0 through 5.4.0 contain a use-after-free vulnerability that could allow a remote attacker to execute arbitrary code.
Original NVD description (English source)
The UpdateHub firmware-over-the-air client parses the CoAP probe response with Zephyr's JSON library in z_impl_updatehub_probe() (subsys/mgmt/updatehub/updatehub.c). The decoder treats every descriptor field as optional — json_obj_parse() returns a bitmask of the fields it actually decoded and never fails on a missing one — so a response that omits the "sha256sum" string leaves the corresponding const char * in the zero-initialised struct resp_probe_any_boards / struct resp_probe_some_boards at NULL. Both metadata branches then computed sha256size = strlen(...objects.sha256sum) + 1 before any validation, dereferencing that NULL pointer; the SHA256_HEX_DIGEST_SIZE test that follows operates on a value the bad read has already produced and cannot prevent it. The metadata is supplied entirely by the network peer: probe_cb() accepts the datagram, runs coap_packet_parse() and copies the payload with no token matching and no cryptographic check. With CONFIG_UPDATEHUB_DTLS unset — the default — start_coap_client() uses plain CoAP over UDP on port 5683 with no peer authentication and resolves the server via unauthenticated DNS, so an on-path attacker, a DNS spoofer, or an off-path attacker who wins the race with a forged source address can deliver the malformed metadata. A probe response as simple as "objects":[[{}],[{}]] suffices, and no user interaction is required because updatehub_autohandler() polls on CONFIG_UPDATEHUB_POLL_INTERVAL. When CONFIG_UPDATEHUB_DTLS=y the trigger narrows to a malicious or compromised update server. The primitive is a read at address zero, not a write, so the impact is availability only. On targets where the low address range is unmapped or protected — MMU-based architectures, builds with CONFIG_NULL_POINTER_EXCEPTION_DETECTION_DWT/_MPU/_PMP, TrustZone non-secure images, and SoCs such as nRF54L whose 0x0–0x400 window is unmapped — the load faults and Zephyr's default fatal handler halts the system, giving a remotely re-triggerable denial of service on every poll. On classic Cortex-M targets where the vector table is readable at address zero the walk usually terminates immediately and the request is rejected by the length check, so the outcome is configuration- and SoC-dependent. There is no memory write, and the copied bytes are only compared against the locally computed image hash, so there is no information-disclosure channel. The fix adds an explicit sha256sum == NULL test that returns UPDATEHUB_METADATA_ERROR ahead of the strlen() in both metadata branches. Debug builds (CONFIG_UPDATEHUB_LOG_LEVEL=4) still format the same pointers with %s in a LOG_DBG() loop that runs before the new checks, so that variant remains in debug configurations only.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS