In the Linux kernel, the following vulnerability has been resolved:
pseries/papr-hvpipe: Fix null ptr deref in papr_hvpipe_dev_create_handle()
commit 6d3789d347a7 ("papr-hvpipe: convert papr_hvpipe_dev_create_handle() to FD_PREPARE()"),
changed the create handle to FD_PREPARE(), but it caused kernel
null-ptr-deref because after call to retain_and_null_ptr(src_info),
src_info is re-used for adding it to the global list.
Getting the following kernel panic in papr_hvpipe_dev_create_handle()
when trying to add src_info to the list.
Kernel attempted to write user page (0) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on write at 0x00000000
Faulting instruction address: 0xc0000000001b44a0
Oops: Kernel access of bad area, sig: 11 [#1]
...
Call Trace:
papr_hvpipe_dev_ioctl+0x1f4/0x48c (unreliable)
sys_ioctl+0x528/0x1064
system_call_exception+0x128/0x360
system_call_vectored_common+0x15c/0x2ec
Now, the error handling with FD_PREPARE's file cleanup and __free(kfree) auto
cleanup is getting too convoluted. This is mainly because we need to
ensure only 1 user get the srcID handle. To simplify this, we allocate
prepare the src_info in the beginning and add it to the global list
under a spinlock after checking that no duplicates exist.
This simplify the error handling where if the FD_ADD fails, we can
simply remove the src_info from the list and consume any pending msg in
hvpipe to be cleared, after src_info became visible in the global list.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-17). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it