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Fencer Vulns
medium 5.9

CVE-2026-96596 json

erl_tar:extract/2 loops forever on a GNU sparse member with a trailing hole

published 2026-10-14 25 d ago modified 2026-10-22 17 d ago also EEF-CVE-2026-96596 , GHSA-phm5-m6cj-5382 , EUVD-2026-101390

cvss
5.9
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in Erlang OTP stdlib (erl_tar module), hexpm hex_core (hex_erl_tar module), hexpm hex (mix_hex_erl_tar module) and erlang rebar3 (r3_hex_erl_tar module) allows an attacker who supplies a tar archive to cause a denial of service via a crafted GNU sparse member.

When erl_tar:extract/1,2 writes a member to disk, erl_tar:stream_to_file_loop/3 reads it in chunks of 65536 bytes by default. For a GNU sparse member whose sparse map ends before its real size, erl_tar:do_sparse_read/3 matches its trailing-hole clause before its zero-length clause. After the chunk is used up, the trailing-hole clause reads zero bytes, does not advance the position, and recurses forever. A 2048-byte archive keeps the extracting process and one scheduler busy until the process is killed. The {max_size, N} option prevents this only when N is below the real size of the member. Extraction with the memory option is not affected.

hex_core ships its own copy of erl_tar as hex_erl_tar, and Hex and rebar3 ship hex_core with prefixed module names (mix_hex_erl_tar and r3_hex_erl_tar). These copies contain the same code and do not call stdlib's erl_tar, so they are affected on any OTP version. OTP 28 is not affected, but an application running on OTP 28 is affected if it extracts archives through an affected version of hex_core, Hex or rebar3.

This issue affects OTP from OTP 29.0 before OTP 29.1.2, corresponding to rebar3 from 3.27.1 before 3.28.0, and stdlib from 8.0 before 8.1.1, and hex from 2.4.2 before 2.5.3; hex_core: from 0.14.0 before 0.20.1.

Patch / fix

  • hex hex_core 0.20.1
  • erlang rebar3 3.28.0
  • hexpm hex_core 0.20.1
  • Erlang OTP 8.1.1, 29.1.2
  • hexpm hex 2.5.3
  • erlang Debian 14 1:29.1.2+dfsg-1
  • erlang-hex Debian 14 2.5.3-2

debian advisories DEBIAN-CVE-2026-96596

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-96596 updated cvss 5.5

erlang: hex_core: hex: rebar3: erl_tar: Denial of Service via crafted GNU sparse TAR archive

  • Red Hat Hardened Images erlang27 27.3.4.18-1.1.hum1
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
23 d ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 5.9 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 5.9 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
hex hex_core
>=0.14.0, <0.20.1
0.20.1

Affected products

  • erlang rebar3
  • hexpm hex_core
  • Erlang OTP
  • hexpm hex

Classification

Weakness
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.