CVE-2025-39726s390/ism: fix concurrency management in ism_cmd()
- 9.8CriticalCVSS base score
- 0.25%Exploitation in 30 daysEPSS · top 83% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: s390/ism: fix concurrency management in ism_cmd() The s390x ISM device data sheet clearly states that only one request-response sequence is allowable per ISM function at any point in time. Unfortunately as of today the s390/ism driver in Linux does not honor that requirement. This patch aims to rectify that. This problem was discovered based on Aliaksei's bug report which states that for certain workloads the ISM functions end up entering error state (with PEC 2 as seen from the logs) after a while and as a consequence connections handled by the respective function break, and for future connection requests the ISM device is not considered -- given it is in a dysfunctional state. During further debugging PEC 3A was observed as well. A kernel message like [ 1211.244319] zpci: 061a:00:00.0: Event 0x2 reports an error for PCI function 0x61a is a reliable indicator of the stated function entering error state with PEC 2. Let me also point out that a kernel message like [ 1211.244325] zpci: 061a:00:00.0: The ism driver bound to the device does not support error recovery is a reliable indicator that the ISM function won't be auto-recovered because the ISM driver currently lacks support for it. On a technical level, without this synchronization, commands (inputs to the FW) may be partially or fully overwritten (corrupted) by another CPU trying to issue commands on the same function. There is hard evidence that this can lead to DMB token values being used as DMB IOVAs, leading to PEC 2 PCI events indicating invalid DMA. But this is only one of the failure modes imaginable. In theory even completely losing one command and executing another one twice and then trying to interpret the outputs as if the command we intended to execute was actually executed and not the other one is also possible. Frankly, I don't feel confident about providing an exhaustive list of possible consequences.
Timeline
ID reserved
By Linux
- 5 months later
· 5 months later
Published
- 14 months later
· 14 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | Medium4.7 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.25% · top 83% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- affected 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 – < 79536c83cf38c285709757c4026da4ae151223ae
- affected 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 – < faf44487dfc80817f178dc8de7a0b73f960d019b
- affected 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 – < 1194ad0d44d66b273a02a3a22882dc863a68d764
- affected 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 – < fafaa4982bedb5532f5952000f714a3e63023f40
- affected 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 – < 897e8601b9cff1d054cdd53047f568b0e1995726
- affected 4.19
- unaffected < 4.19
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.101 – ≤ 6.6.*
- unaffected 6.12.41 – ≤ 6.12.*
- unaffected 6.15.9 – ≤ 6.15.*
- unaffected 6.16 – ≤ *
References
References5
- https://git.kernel.org/stable/c/79536c83cf38c285709757c4026da4ae151223ae (opens in a new tab)
- https://git.kernel.org/stable/c/faf44487dfc80817f178dc8de7a0b73f960d019b (opens in a new tab)
- https://git.kernel.org/stable/c/1194ad0d44d66b273a02a3a22882dc863a68d764 (opens in a new tab)
- https://git.kernel.org/stable/c/fafaa4982bedb5532f5952000f714a3e63023f40 (opens in a new tab)
- https://git.kernel.org/stable/c/897e8601b9cff1d054cdd53047f568b0e1995726 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-33998 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-39726)Record last updated .