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Connection error-path memory leak in OFFIS DCMTK
CVE-2026-35505 is a high-severity memory management flaw in OFFIS DCMTK affecting versions 3.7.0 and earlier. The vulnerability is caused by missing release of allocated memory on an association-handling error path. According to the provided context, an unauthenticated client can send a crafted DICOM A-ASSOCIATE-RQ in which presentation-context structures are parsed and allocated, and a later presentation context triggers a translation failure or similar parse/validation error before the parsed PDU graph is freed. Repeating these malformed connection requests leaks memory over time. The context also notes an analogous SCU-side error path in long-running DCMTK clients when parsing a malformed A-ASSOCIATE-AC from a rogue server. The issue is classified as CWE-401 (Missing Release of Memory after Effective Lifetime).
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation allows remote unauthenticated denial of service through memory exhaustion. In single-process deployments, including the default single-process mode referenced for affected services such as storescp, repeated exploitation can cause resident memory usage to grow until the process is killed or otherwise stops accepting DICOM connections. The affected port may remain unresponsive until the service is restarted. On long-running client-side deployments, a rogue server may similarly induce memory growth in the client process via the analogous malformed response path.
If you can’t patch tonight, do this now.
Until patched, restrict DICOM services to trusted networks and prevent exposure to untrusted clients or servers. Prefer multi-process or forked deployment modes where available to reduce the blast radius of per-connection failures and lower the likelihood that a single leaking process will take down the entire service. Monitor process memory consumption and service health, and restart affected services if they become unresponsive. Network filtering or protocol-aware controls that block malformed or unexpected association requests may reduce exploitability, but are compensating controls rather than a substitute for patching.
Patch, then assume compromise.
Upgrade to a fixed DCMTK release once available from OFFIS or the downstream product vendor. The provided context states that the fix was committed upstream in DCMTK master as commit 2312891a8, but had not yet been included in a release at the time of the advisory. Organizations using embedded or redistributed DCMTK should obtain vendor-provided patched builds or backport the upstream fix into their maintained package. Confirm that all affected DCMTK components, including server and any long-running client use cases, are updated.
No public exploits tracked yet. Mallory keeps watching.
6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.