CVE-2025-39880 — libceph: fix invalid accesses to ceph_connection_v1_info
In the Linux kernel, the following vulnerability has been resolved: libceph: fix invalid accesses to ceph_connection_v1_info There is a place where generic code in messenger.c is reading and another place where it is writing to con->v1 union member without checking that the union member is active (i.e. msgr1 is in use). On 64-bit systems, con->v1.auth_retry overlaps with con->v2.out_iter, so such a read is almost guaranteed to return a bogus value instead of 0 when msgr2 is in use. This ends up being fairly benign because the side effect is just the invalidation of the authorizer and successive fetching of new tickets. con->v1.connect_seq overlaps with con->v2.conn_bufs and the fact that it's being written to can cause more serious consequences, but luckily it's not something that happens often.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.3% (30-day exploitation probability)+4
- Technical severity (high)+6
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Debian Debian Linux, Linux Linux, Linux Linux Kernel).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Debian | Debian Linux | version 11.0 | Vulnerable | NIST National Vulnerability Database |
| Linux | Linux | version 5.11≥ cd1a677cad994021b19665ed476aea63f5d54f31 and < cdbc9836c7afadad68f374791738f118263c5371≥ cd1a677cad994021b19665ed476aea63f5d54f31 and < 6bd8b56899be0b514945f639a89ccafb8f8dfaef≥ cd1a677cad994021b19665ed476aea63f5d54f31 and < 35dbbc3dbf8bccb2d77c68444f42c1e6d2d27983≥ cd1a677cad994021b19665ed476aea63f5d54f31 and < 23538cfbeed87159a5ac6c61e7a6de3d8d4486a8≥ cd1a677cad994021b19665ed476aea63f5d54f31 and < 591ea9c30737663a471b2bb07b27ddde86b020d5≥ cd1a677cad994021b19665ed476aea63f5d54f31 and < ea12ab684f8ae8a6da11a22c78d94a79e2163096 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel |
version 6.17-rc4version 6.17-rc5version 6.17-rc3version 6.17-rc2version 6.17-rc1≥ 6.13 and < 6.16.8≥ 6.7 and < 6.12.48≥ 6.2 and < 6.6.107 and 2 more≥ 5.16 and < 6.1.153≥ 5.11 and < 5.15.194 |
Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 9.8 | CVSS 3.1 | Critical | 3.9 | 5.9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 9.8 | CVSS 3.1 | Critical | — | — | Linux via CVE Program (cve.org) e CISA ADP |
| 7.8 | CVSS 3.1 | High | 1.8 | 5.9 | nvd@nist.gov via NIST National Vulnerability Database |
| 7.8 | CVSS 3.1 | High | — | — | GitHub, Inc. via GitHub Security Advisories |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- SSVC assessment updated
- Record published
- Fix documented
- Affected products added · linux/linux kernel, debian/debian linux
- CVSS changed · 7.8
- Source status changed · → Modified
- Record created in this database
- 2025
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 15, 2026 – Oct 15, 2026
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
9 on the record
- git.kernel.org/stable/c/591ea9c30737663a471b2bb07b27ddde86b020d5
- git.kernel.org/stable/c/ea12ab684f8ae8a6da11a22c78d94a79e2163096
- git.kernel.org/stable/c/cdbc9836c7afadad68f374791738f118263c5371
- git.kernel.org/stable/c/35dbbc3dbf8bccb2d77c68444f42c1e6d2d27983
- git.kernel.org/stable/c/23538cfbeed87159a5ac6c61e7a6de3d8d4486a8
- git.kernel.org/stable/c/6bd8b56899be0b514945f639a89ccafb8f8dfaef
- github.com/advisories/GHSA-f84f-657f-x94w
- nvd.nist.gov/vuln/detail/CVE-2025-39880
- lists.debian.org/debian-lts-announce/2025/10/msg00008.html
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 12h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 12h
- Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2025-39880 is "libceph: fix invalid accesses to ceph_connection_v1_info", rated High. It affects Debian Linux (Debian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 0.33% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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