[HIGH] CVE-2026-74578 — CVSS 7.1 (August 16, 2026)

A HIGH-severity vulnerability identified as CVE-2026-74578 has been published on August 16, 2026 with a CVSS base score of 7.1. This security advisory provides a detailed breakdown of the vulnerability, its potential impact, weakness classification, and actionable steps to protect your systems.

Vulnerability Details

CVE ID: CVE-2026-74578
Severity: HIGH
CVSS Score: 7.1
Published: August 16, 2026

Technical Description

In the Linux kernel, the following vulnerability has been resolved: crypto: algif_skcipher – force synchronous processing on trees without ctx->state The AIO/async path in skcipher_recvmsg() passes the socket-wide ctx->iv directly into the skcipher request. After io_submit() the socket lock is dropped and the request is processed asynchronously, so a concurrent sendmsg(ALG_SET_IV) can overwrite ctx->iv and make the in-flight request run under an attacker-controlled IV. For CTR/stream modes this is IV/keystream reuse and lets an unprivileged user recover the plaintext of a concurrent operation. Snapshotting ctx->iv into per-request storage for the async path is not sufficient. For ciphers with statesize == 0 – which includes cbc and ctr – the MSG_MORE inter-chunk IV chaining is carried solely by the in-place req->iv writeback, which a snapshot redirects into per-request memory that af_alg_free_resources() releases on completion, silently producing wrong output. Writing the IV back from the completion callback instead is not possible either: that would require lock_sock() there, but the callback can run in softirq/atomic context, so it must not sleep. Make the operation synchronous instead, which removes both the IV race and any writeback race. This is equivalent to the upstream resolution, commit fcc77d33a34c ("net: Remove support for AIO on sockets"), which removed the AIO socket path across net/ entirely and so produces the same end state for this file. This patch deviates from that commit deliberately: rather than removing AIO socket support tree-wide, which would be far too invasive for stable, it removes only the AIO branch in crypto/algif_skcipher.c. io_submit() now completes synchronously; AF_ALG async is rarely used in practice. The -EIOCBQUEUED check in skcipher_recvmsg() is now dead but harmless, and is left alone to keep the fix minimal. Tested on 6.6.y: attacker IV injection dropped from 2296/200000 to 0/200000 after the change; MSG_MORE chunked CTR output bit-identical to single-shot.

Potential Impact

If exploited, this high-severity vulnerability could allow an attacker to compromise sensitive data confidentiality, tamper with system integrity. Organizations running affected software should treat this as a priority remediation item.

Recommended Action

No official patch is available yet. Until one is released:

1. Monitor the official NVD page and vendor channels for patch announcements.
2. Restrict access to the affected system or service where possible.
3. Apply network-level mitigations such as firewall rules or WAF policies.
4. Enable logging and alerting for anomalous activity related to this vulnerability.
5. Review your incident response plan in case of active exploitation.

View full details on NVD →

References

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• Reference 5

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