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CVE-2026-74578— crypto: algif_skcipher - force synchronous processing on trees without ctx->state

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于crypto algif_skcipher的异步路径中，socket锁释放后并发sendmsg(ALG_SET_IV)可覆盖ctx->iv，导致IV/密钥流重用，可能允许无特权用户恢复并发操作的明文。

CVSS 7.1 · High EPSS 0.19% · P9

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< bf09b0be8e851f050e98da702d247c14d81b591a affected
e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< 73dd3bf704ca6c20639de70c08e9a10bee904a95 affected
e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< f1a87ca0843d74482402a206ea2dfb315ee9acbd affected
e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< 7b91e51d0eb7cbb07f7f086f9176bd93dbbc85dd affected
e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< 60eafc7b08c6689ea3ad39eff8d97aefc8a087c7 affected
e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< d7860b682da55433b5da0591b0e4c1982ecd2689 affected
e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< b05defc41b27c7d0c05c45f67bf5b91c28f93669 affected
e870456d8e7c8d57c059ea479b5aadbb55ff4c3a< fcc77d33a34cf271702e8daafb6c593e4626776d affected
… +10 more rows
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I. Basic Information for CVE-2026-74578

Vulnerability Information
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Vulnerability Title
crypto: algif_skcipher - force synchronous processing on trees without ctx->state
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于crypto algif_skcipher的异步路径中，socket锁释放后并发sendmsg(ALG_SET_IV)可覆盖ctx->iv，导致IV/密钥流重用，可能允许无特权用户恢复并发操作的明文。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux e870456d8e7c8d57c059ea479b5aadbb55ff4c3a ~ bf09b0be8e851f050e98da702d247c14d81b591a -
Linux Linux 4.14 -

II. Public POCs for CVE-2026-74578

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III. Intelligence Information for CVE-2026-74578

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Patches & Fixes for CVE-2026-74578 (7)

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74578

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