CVE-2026-53391: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr
Vulnerability summary
CVE-2026-53391 is a high (CVSS 7.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 44% of scored vulnerabilities.
Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 43 · Related 38Timeline
- 19-07-2026PublishedVulnerability first disclosed.
- 19-10-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr nfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a netaddr4 from a GETDEVICEINFO multipath-DS body, then immediately calls strrchr(buf, '.') to locate the port separator. Both decodes use xdr_stream_decode_string_dup(), and the current code checks only "nlen < 0" / "rlen < 0" before dereferencing the returned string. When the on-wire opaque has length zero, xdr_stream_decode_opaque_inline() returns 0 and xdr_stream_decode_string_dup() falls through to its "*str = NULL; return ret" tail, leaving buf NULL with a return value of 0. The "< 0" check does not catch this, and the next line is strrchr(NULL, '.'), a kernel NULL pointer dereference reachable from any pNFS-flexfile client mounted against a malicious or compromised metadata server. Reject the zero-length cases explicitly so the decoder fails with -EBADMSG (treated as a malformed GETDEVICEINFO body) instead of panicking the client.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.52%
Chance of exploitation in the next 30 days
Percentile
44%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.52% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu169 products
- linuxAll versions (No fix recorded) | < 5.15.0-198.208 | < 6.8.0-147.147 | < 7.0.0-31.31
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1117.124 | < 6.8.0-1067.70 | < 7.0.0-1012.12
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 6b7f3cf96364eaf597940cb5c68a682894829915, < 76b94cbd32aacf36a641956385a852635c6802b9 | ≥ 6b7f3cf96364eaf597940cb5c68a682894829915, < c8e4e0c701d0192a2efb6df059c0f9e19678c23d | ≥ 6b7f3cf96364eaf597940cb5c68a682894829915, < 6c344fff2feff9d4d716d8e4ad40e9b5040ee5ea | ≥ 6b7f3cf96364eaf597940cb5c68a682894829915, < 427ab81a811dab4bca9d19f82eec5847ae42646e | ≥ 6b7f3cf96364eaf597940cb5c68a682894829915, < 012d37a568bfbb2c9686f03ade75560bc7139956 | ≥ 6b7f3cf96364eaf597940cb5c68a682894829915, < 30aae62e50b4e074a90a9a5e15246548fbdc1182 | ≥ 6b7f3cf96364eaf597940cb5c68a682894829915, < 41fe0f7b84f0cb822ae10ab08592996a592b2a25 | 4.0
- linux_kernel≥ 4.0, < 5.15.211 | ≥ 5.16, < 6.1.177 | ≥ 6.2, < 6.6.144 | ≥ 6.7, < 6.12.95 | ≥ 6.13, < 6.18.38 | ≥ 6.19, < 7.1.3
Debian1 product
- linux< 6.1.177-1 | < 6.12.95-1 | < 7.1.3-1
3 vendors · 172 products
