{"basis":"claimed","id":"CVE-2026-87044","name":"Memory leak in the Mbed TLS crypto shim on failed cipher/AEAD operations leads to remotely triggered crypto denial of service","vendorProject":"zephyrproject","product":"zephyr","publishedAt":"2026-11-04","cvss":{"score":6.5,"severity":"MEDIUM","version":"3.1"},"exploited":null,"epss":null,"coverage":{"cloudflare":{"status":"none","firstOn":null,"daysToRule":null},"aws":{"status":"none","firstOn":null,"daysToRule":null},"azure":{"status":"none","firstOn":null,"daysToRule":null},"google":{"status":"none","firstOn":null,"daysToRule":null},"fastly":{"status":"none","firstOn":null,"daysToRule":null},"vercel":{"status":"none","firstOn":null,"daysToRule":null},"f5":{"status":"none","firstOn":null,"daysToRule":null},"akamai":{"status":"no_source","firstOn":null,"daysToRule":null},"crs":{"status":"none","firstOn":null,"daysToRule":null}},"title":"Memory leak in the Mbed TLS crypto shim on failed cipher/AEAD operations leads to remotely triggered crypto denial of service","description":"The Mbed TLS crypto shim driver in drivers/crypto/crypto_mbedtls_shim.c drives PSA multipart cipher and AEAD operations. In mbedtls_cbc() and mbedtls_aead(), every error path after a successful psa_cipher_encrypt_setup() / psa_aead_decrypt_setup() returned directly without calling psa_cipher_abort() / psa_aead_abort(). Because the abort is the only thing that reaches mbedtls_cipher_free(), each failed operation permanently leaked the heap-allocated mbedtls_aes_context (roughly 288 bytes) that setup had allocated from Mbed TLS's fixed static heap (_mbedtls_heap[CONFIG_MBEDTLS_HEAP_SIZE], default 512 bytes). With CONFIG_PSA_CRYPTO_PROVIDER_TFM the leaked object is instead a finite secure-partition multipart-operation slot.\n\nThe failure is chosen by an unauthenticated attacker. With CONFIG_NET_L2_IEEE802154_SECURITY backed by this driver, ieee802154_decrypt_auth() in subsys/net/l2/ieee802154/ieee802154_security.c invokes cipher_ccm_op() on every received secured frame, with no authentication ahead of the MIC check. A device in radio range can transmit a stream of syntactically valid 802.15.4 frames carrying a bogus MIC; each one makes psa_aead_verify() fail and leaks a block. The CBC path is reachable the same way through the OSDP secure channel, where CONFIG_OSDP_SC_ENABLED selects this shim and osdp_encrypt() / osdp_decrypt() leave out_buf_max unset, so every operation fails inside psa_cipher_update().\n\nExhausting the Mbed TLS heap — which the default configuration reaches after a couple of failed operations, and any realistic configuration reaches in well under a second of frames — makes all subsequent mbedtls_calloc() calls fail. Every later cryptographic operation in the image then fails permanently, including link-layer security and any TLS/DTLS sharing the same heap, until the device is rebooted. There is no memory corruption or information disclosure: frames with an invalid MIC are still rejected, so the impact is limited to availability.\n\nThe fix routes all post-setup failures in mbedtls_cbc() and mbedtls_aead() through a common error: label that calls the matching PSA abort before returning. Setup failures need no change, since the PSA core aborts the operation itself when setup fails.","cwes":["CWE-401"],"vendors":[{"vendor":"cloudflare","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"aws","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"azure","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"google","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"fastly","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"vercel","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"f5","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"akamai","status":"no_source","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"crs","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]}],"updatedAt":"2026-11-04T07:30:09.088Z","cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","ssvc":null,"kevAction":null,"kevNotes":null,"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/8e7e9e9bf9f0b1a7acd12ef3d6d38473b1ce6d43","name":"Fix commit","tags":["patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-r8x3-637f-c986","name":"GHSA-r8x3-637f-c986","tags":[]}],"affected":[{"vendor":"zephyrproject","product":"zephyr","affected":["4.4.0 to before 4.5.0"],"fixed":[]}],"briefing":{"status":{"id":"monitor","label":"Monitor"},"why":"No edge WAF vendor names it in a changelog, so default managed rules may or may not catch it. Exploitation in the wild is not established by CISA KEV.","who":"Teams running zephyrproject zephyr (4.4.0 to before 4.5.0).","what_to_do":[{"text":"Apply the vendor's fix; the advisory lists the affected and fixed versions.","href":"https://github.com/zephyrproject-rtos/zephyr/commit/8e7e9e9bf9f0b1a7acd12ef3d6d38473b1ce6d43","linkText":"Fix commit"},{"text":"Do not rely on WAF defaults: no edge vendor names this CVE. Restrict access to the vulnerable component or add a custom rule until it is patched.","href":"#edge","linkText":"Edge coverage"},{"text":"Check which WAF sits in front of your site and whether it covers this CVE.","href":"#check","linkText":"Check your domain"}],"evidence":[{"heading":"CVE record","text":"CVSS 3.1 6.5 (medium). Weakness: CWE-401.","links":[{"label":"CVE-2026-87044","href":"https://www.cve.org/CVERecord?id=CVE-2026-87044"},{"label":"NVD","href":"https://nvd.nist.gov/vuln/detail/CVE-2026-87044"}]},{"heading":"Vendor advisory","text":"Fixes and mitigations the CVE record links to. Check affected builds against the vendor, including backports.","links":[{"label":"Fix commit","href":"https://github.com/zephyrproject-rtos/zephyr/commit/8e7e9e9bf9f0b1a7acd12ef3d6d38473b1ce6d43"}]},{"heading":"Exploit evidence","text":"No public exploit code found in Exploit-DB, Metasploit, nuclei-templates or GitHub. That does not mean none exists.","links":[]},{"heading":"CISA KEV","text":"Not in the KEV catalog (catalog 2026.11.03, checked 2026-11-04). Absence from KEV is not evidence that it cannot be exploited.","links":[{"label":"CISA KEV catalog","href":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog"}]},{"heading":"WAF vendor statements","text":"No edge vendor changelog names it.","links":[]}],"agent_prompt":"Assess whether the infrastructure available to you is affected by CVE-2026-87044 (Memory leak in the Mbed TLS crypto shim on failed cipher/AEAD operations leads to remotely triggered crypto denial of service). Perform a read-only assessment within your authorized access. Do not send exploit traffic, scan third-party systems, change configuration or restart services.\n\n1. Verify the CVE record at https://www.cve.org/CVERecord?id=CVE-2026-87044 and the vendor advisories (https://github.com/zephyrproject-rtos/zephyr/commit/8e7e9e9bf9f0b1a7acd12ef3d6d38473b1ce6d43). Establish affected and fixed versions, including vendor backports. The record lists: zephyrproject zephyr: affected 4.4.0 to before 4.5.0. Cite sources and retrieval dates; flag anything you cannot verify.\n2. Inventory deployments of zephyrproject zephyr: asset, environment, owner where known, installed version or build, and how you confirmed it (package metadata, a version endpoint, image tags). An image tag alone does not prove the running version.\n3. Identify which deployments are reachable from the internet or untrusted networks, and through which paths (direct origin, load balancer, CDN or WAF).\n4. Assess compensating controls separately from patch status. Current edge WAF coverage for this CVE: no edge WAF vendor names it. Live data: https://cve.vigilbase.com/api/v1/cves/CVE-2026-87044. Check whether the rule is enabled and in block mode on each path, and whether any path bypasses the WAF. A WAF rule is not a patch.\n5. Check logs on exposed instances for requests matching the public exploit, if your access allows.\n\nReturn a short summary and a table: asset | version/build | assessment (affected, fixed, not applicable, unknown) | exposure | compensating control | evidence | next action. List what you could not assess and the access needed to resolve it. Do not infer absence of compromise from patch status or a lack of alerts.\n\nRemediation guidance: Apply the vendor's fix; the advisory lists the affected and fixed versions. Do not rely on WAF defaults: no edge vendor names this CVE. Restrict access to the vulnerable component or add a custom rule until it is patched.\nMore: https://cve.vigilbase.com/cve/CVE-2026-87044"},"measured":[],"sightings":null,"social":{"total":1,"first_seen":"2026-11-04T07:25:23.471Z","daily":[{"day":"2026-10-22","posts":0},{"day":"2026-10-23","posts":0},{"day":"2026-10-24","posts":0},{"day":"2026-10-25","posts":0},{"day":"2026-10-26","posts":0},{"day":"2026-10-27","posts":0},{"day":"2026-10-28","posts":0},{"day":"2026-10-29","posts":0},{"day":"2026-10-30","posts":0},{"day":"2026-10-31","posts":0},{"day":"2026-11-01","posts":0},{"day":"2026-11-02","posts":0},{"day":"2026-11-03","posts":0},{"day":"2026-11-04","posts":1}],"top_posts":[{"source":"bluesky","kind":"post","url":"https://bsky.app/profile/cve.skyfleet.blue/post/cnd7tibzmlnkh","author":"cve.skyfleet.blue","author_name":"CVE Alerts ","avatar_url":"https://cdn.bsky.app/img/avatar/plain/did:plc:myutg2pwkjbukv7pq2hp5mtl/bafkreidzrx72dabuipp2ej2gldupqzv5nbtbez7tv4n26ekzjsot6ocdam","text":"CVE-2026-87044 - Memory leak in the Mbed TLS crypto shim on failed cipher/AEAD operations leads to remotely triggered crypto denial of service\nCVE ID : CVE-2026-87044\n \n Published : Nov. 4, 2026, 6:17 a.m. | 47 minutes ago\n \n Description : The Mbed TLS crypto shim driver in dr...","engagement":0,"posted_at":"2026-11-04T07:25:23.471Z"}],"exploit_repositories":[]}}