CVE-2024-26800: tls: fix use-after-free on failed backlog decryption
In the Linux kernel, the following vulnerability has been resolved:
tls: fix use-after-free on failed backlog decryption
When the decrypt request goes to the backlog and crypto_aead_decrypt
returns -EBUSY, tls_do_decryption will wait until all async
decryptions have completed. If one of them fails, tls_do_decryption
will return -EBADMSG and tls_decrypt_sg jumps to the error path,
releasing all the pages. But the pages have been passed to the async
callback, and have already been released by tls_decrypt_done.
The only true async case is when crypto_aead_decrypt returns
-EINPROGRESS. With -EBUSY, we already waited so we can tell
tls_sw_recvmsg that the data is available for immediate copy, but we
need to notify tls_decrypt_sg (via the new ->async_done flag) that the
memory has already been released.
Security readout for executives and security teams
Plain-English summary
This is a Linux kernel memory-safety bug in kernel TLS handling. Under a failed asynchronous decrypt backlog condition, pages can be released twice or used after release. Business impact is not fully quantified in the sources, but kernel memory errors can affect system stability and potentially security boundaries.
Executive priority
Treat as a kernel patch-management item with uncertain severity. Prioritize normal-to-expedited remediation where Linux systems are exposed, business-critical, or use kernel TLS, but the supplied sources do not justify emergency response claims.
Technical view
The flaw is in Linux kernel TLS software receive decryption. When crypto_aead_decrypt returns -EBUSY, tls_do_decryption waits for async decryptions; if one fails, tls_decrypt_sg follows an error path that releases pages already released by tls_decrypt_done. The fix adds async_done handling to avoid reusing freed memory.
Likely exposure
Exposure appears limited to Linux systems running affected kernel code paths that use kernel TLS receive processing with asynchronous crypto backlog behavior. The bundle names Linux kernel stable commits and versions, but distro-specific affected packages are not provided.
Exploitation context
The source bundle does not report active exploitation, and KEV is false. No public exploit status, attack prerequisites, or practical impact details are provided in the supplied evidence.
Researcher notes
Evidence supports a use-after-free in the TLS receive decrypt error path involving -EBUSY, async completion, and page lifetime tracking. The bundle lacks CVSS, CWE, exploitability analysis, and distro package ranges, so validation should be source-and-vendor specific.
Mitigation direction
Check your Linux distribution advisory for CVE-2024-26800 package status.
Update kernels to vendor-supported builds containing the referenced upstream stable fixes.
Prioritize internet-facing or high-availability Linux systems using kernel TLS features.
If no vendor fix is available, follow vendor guidance for temporary risk reduction.
Validation and detection
Inventory Linux kernel versions across servers, appliances, and container hosts.
Map installed kernels to distribution advisories for CVE-2024-26800.
Confirm whether kernel TLS is enabled or used by workloads.
Verify patched systems booted into the updated kernel, not only installed it.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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